diff --git a/src/app/components/HardpointSlot.jsx b/src/app/components/HardpointSlot.jsx
index 0c5773a8..c9fc6ece 100644
--- a/src/app/components/HardpointSlot.jsx
+++ b/src/app/components/HardpointSlot.jsx
@@ -1,6 +1,8 @@
 import React from 'react';
 import Slot from './Slot';
-import { DamageKinetic, DamageThermal, DamageExplosive, MountFixed, MountGimballed, MountTurret, Modifications } from './SvgIcons';
+import { DamageKinetic, DamageThermal, DamageExplosive, MountFixed, MountGimballed, MountTurret, ListModifications } from './SvgIcons';
+import { Modifications } from 'coriolis-data/dist';
+
 
 /**
  * Hardpoint / Utility Slot
@@ -36,6 +38,7 @@ export default class HardpointSlot extends Slot {
     if (m) {
       let classRating = `${m.class}${m.rating}${m.missile ? '/' + m.missile : ''}`;
       let { drag, drop } = this.props;
+      let validMods = Modifications.validity[m.grp] || [];
 
       return <div className='details' draggable='true' onDragStart={drag} onDragEnd={drop}>
         <div className={'cb'}>
@@ -59,7 +62,7 @@ export default class HardpointSlot extends Slot {
           { m.range && !m.dps ? <div className={'l'}>{translate('Range')} : {formats.round(m.range / 1000)}{u.km}</div> : null }
           { m.shieldmul ? <div className={'l'}>+{formats.rPct(m.shieldmul)}</div> : null }
           { m.ammo >= 0 ? <div className={'l'}>{translate('ammo')}: {formats.int(m.clip)}/{formats.int(m.ammo)}</div> : null }
-	  <div className={'r'}><Modifications /></div>
+	  { validMods.length > 0 ? <div className='r' ><ListModifications /></div> : null }
         </div>
       </div>;
     } else {
diff --git a/src/app/components/InternalSlot.jsx b/src/app/components/InternalSlot.jsx
index fa29f27c..6dcc25f3 100644
--- a/src/app/components/InternalSlot.jsx
+++ b/src/app/components/InternalSlot.jsx
@@ -1,6 +1,7 @@
 import React from 'react';
 import Slot from './Slot';
-import { Modifications } from './SvgIcons';
+import { ListModifications } from './SvgIcons';
+import { Modifications } from 'coriolis-data/dist';
 
 /**
  * Internal Slot
@@ -19,6 +20,7 @@ export default class InternalSlot extends Slot {
     if (m) {
       let classRating = m.class + m.rating;
       let { drag, drop } = this.props;
+      let validMods = Modifications.validity[m.grp] || [];
 
       return <div className='details' draggable='true' onDragStart={drag} onDragEnd={drop}>
         <div className={'cb'}>
@@ -42,7 +44,7 @@ export default class InternalSlot extends Slot {
           { m.rangeLS === null ? <div className={'l'}>∞{u.Ls}</div> : null }
           { m.rangeRating ? <div className={'l'}>{translate('range')}: {m.rangeRating}</div> : null }
           { m.armouradd ? <div className={'l'}>+{m.armouradd} <u className='cap'>{translate('armour')}</u></div> : null }
-          <div className={'r'}><Modifications /></div>
+	  { validMods.length > 0 ? <div className='r' ><ListModifications /></div> : null }
         </div>
       </div>;
     } else {
diff --git a/src/app/components/StandardSlot.jsx b/src/app/components/StandardSlot.jsx
index c9fa45ea..94e177e4 100644
--- a/src/app/components/StandardSlot.jsx
+++ b/src/app/components/StandardSlot.jsx
@@ -4,8 +4,9 @@ import TranslatedComponent from './TranslatedComponent';
 import { jumpRange } from '../shipyard/Calculations';
 import { diffDetails } from '../utils/SlotFunctions';
 import AvailableModulesMenu from './AvailableModulesMenu';
-import { Modifications } from './SvgIcons';
+import { ListModifications } from './SvgIcons';
 import Slider from './Slider';
+import { Modifications } from 'coriolis-data/dist';
 
 /**
  * Standard Slot
@@ -33,6 +34,7 @@ export default class StandardSlot extends TranslatedComponent {
     let m = slot.m;
     let classRating = m.class + m.rating;
     let menu;
+    let validMods = m == null ? [] : (Modifications.validity[m.grp] || []);
 
     if (this.props.selected) {
       menu = <AvailableModulesMenu
@@ -66,10 +68,7 @@ export default class StandardSlot extends TranslatedComponent {
                 { m.weaponcapacity ? <div className='l'>{translate('WEP')}: {m.weaponcapacity}{units.MJ} / {m.weaponrecharge}{units.MW}</div> : null }
                 { m.systemcapacity ? <div className='l'>{translate('SYS')}: {m.systemcapacity}{units.MJ} / {m.systemrecharge}{units.MW}</div> : null }
                 { m.enginecapacity ? <div className='l'>{translate('ENG')}: {m.enginecapacity}{units.MJ} / {m.enginerecharge}{units.MW}</div> : null }
-              <div className={'r'}><Modifications /></div>
-            </div>
-            <div className={'cb'} >
-              <Slider onChange={this._updateSliderValue.bind(this)} min={-1} max={1} percent={this._getSliderValue()} />
+	        { validMods.length > 0 ? <div className='r' ><ListModifications /></div> : null }
             </div>
           </div>
         </div>
@@ -77,10 +76,12 @@ export default class StandardSlot extends TranslatedComponent {
       </div>
     );
   }
+  // {validMods.length > 0 ? <div className='cb' ><Slider onChange={this._updateSliderValue.bind(this)} min={-1} max={1} percent={this._getSliderValue()}/></div> : null }
 
   /**
    * Update power usage modification given a slider value.
    * Note that this is a temporary function until we have a slider section
+   * @param {Number} value The value of the slider
    */
   _updateSliderValue(value) {
     let m = this.props.slot.m;
@@ -93,6 +94,7 @@ export default class StandardSlot extends TranslatedComponent {
   /**
    * Obtain slider value from a power usage modification.
    * Note that this is a temporary function until we have a slider section
+   * @return {Number} value The value of the slider
    */
   _getSliderValue() {
     let m = this.props.slot.m;
diff --git a/src/app/components/SvgIcons.jsx b/src/app/components/SvgIcons.jsx
index 984415d1..50c13e16 100644
--- a/src/app/components/SvgIcons.jsx
+++ b/src/app/components/SvgIcons.jsx
@@ -489,9 +489,9 @@ export class Rocket extends SvgIcon {
 }
 
 /**
- * Modifications (engineers)
+ * ListModifications (engineers)
  */
-export class Modifications extends SvgIcon {
+export class ListModifications extends SvgIcon {
   /**
    * Overriden view box
    * @return {String} view box
diff --git a/src/app/shipyard/Module.js b/src/app/shipyard/Module.js
index acf666a0..d3377e6b 100755
--- a/src/app/shipyard/Module.js
+++ b/src/app/shipyard/Module.js
@@ -32,20 +32,20 @@ export default class Module {
    * @return {Number}        The value of the modification, as a decimal value from -1 to 1
    */
   getModValue(modId) {
-    return this.mods ? this.mods[modId] / 100000 : null;
+    return this.mods ? this.mods[modId] / 10000 : null;
   }
 
   /**
    * Set a value for a given modification ID
    * @param {Number} modId   The ID of the modification
-   * @param {Number} val     The value of the modification, as a decimal value from -1 to 1
+   * @param {Number} value   The value of the modification, as a decimal value from -1 to 1
    */
   setModValue(modId, value) {
     if (value == null || value == 0) {
       delete this.mods[modId];
     } else {
-      // Store value with 3dp
-      this.mods[modId] = Math.round(value * 100000);
+      // Store value with 2dp
+      this.mods[modId] = Math.round(value * 10000);
     }
   }
 
diff --git a/src/app/shipyard/Ship.js b/src/app/shipyard/Ship.js
index 5905170a..36e6fe85 100755
--- a/src/app/shipyard/Ship.js
+++ b/src/app/shipyard/Ship.js
@@ -434,7 +434,7 @@ export default class Ship {
 
     this.bulkheads.m = null;
     this.useBulkhead(comps && comps.bulkheads ? comps.bulkheads : 0, true);
-    this.bulkheads.m.mods = mods && mods[0] ? mods[0] : {}
+    this.bulkheads.m.mods = mods && mods[0] ? mods[0] : {};
     this.cargoHatch.priority = priorities ? priorities[0] * 1 : 0;
     this.cargoHatch.enabled = enabled ? enabled[0] * 1 : true;
     this.cargoHatch.mods = mods ? mods[0] : {};
@@ -896,8 +896,8 @@ export default class Ship {
 
     let bulkheadMods = new Array();
     if (this.bulkheads.m && this.bulkheads.m.mods) {
-      for (var modKey in this.bulkheads.m.mods) {
-        bulkheadMods.push(modKey + ':' + Math.round(this.bulkheads.m.getModValue(modKey) * 100000));
+      for (let modKey in this.bulkheads.m.mods) {
+        bulkheadMods.push(modKey + ':' + Math.round(this.bulkheads.m.getModValue(modKey) * 10000));
       }
     }
     allMods.push(bulkheadMods.join(';'));
@@ -905,8 +905,8 @@ export default class Ship {
     for (let slot of this.standard) {
       let slotMods = new Array();
       if (slot.m && slot.m.mods) {
-        for (var modKey in slot.m.mods) {
-          slotMods.push(modKey + ':' + Math.round(slot.m.getModValue(modKey) * 100000));
+        for (let modKey in slot.m.mods) {
+          slotMods.push(modKey + ':' + Math.round(slot.m.getModValue(modKey) * 10000));
         }
       }
       allMods.push(slotMods.join(';'));
@@ -914,8 +914,8 @@ export default class Ship {
     for (let slot of this.hardpoints) {
       let slotMods = new Array();
       if (slot.m && slot.m.mods) {
-        for (var modKey in slot.m.mods) {
-          slotMods.push(modKey + ':' + Math.round(slot.m.getModValue(modKey) * 100000));
+        for (let modKey in slot.m.mods) {
+          slotMods.push(modKey + ':' + Math.round(slot.m.getModValue(modKey) * 10000));
         }
       }
       allMods.push(slotMods.join(';'));
@@ -923,8 +923,8 @@ export default class Ship {
     for (let slot of this.internal) {
       let slotMods = new Array();
       if (slot.m && slot.m.mods) {
-        for (var modKey in slot.m.mods) {
-          slotMods.push(modKey + ':' + Math.round(slot.m.getModValue(modKey) * 100000));
+        for (let modKey in slot.m.mods) {
+          slotMods.push(modKey + ':' + Math.round(slot.m.getModValue(modKey) * 10000));
         }
       }
       allMods.push(slotMods.join(';'));