diff --git a/devTools/types/extensions.d.ts b/devTools/types/extensions.d.ts
index b9b32455c007436a957ba03a8cf9afb982b2aeef..3b69613e15631488e2508f0b97dd86b14776765b 100644
--- a/devTools/types/extensions.d.ts
+++ b/devTools/types/extensions.d.ts
@@ -3,6 +3,16 @@ interface MousetrapStatic {
 	record(callback: (this: MousetrapStatic, sequence: string[]) => void): void;
 }
 
+interface Number {
+	/**
+	 * Returns whether the value is between the given bounds, with optional inclusivity.
+	 * @param min The minimum value to check against.
+	 * @param max The maximum value to check against.
+	 * @param inclusive Whether to include the bounds values.
+	 */
+	 isBetween(min: number, max: number, inclusive?: boolean): boolean;
+}
+
 // d3-dtree
 
 declare namespace d3dTree {
diff --git a/js/extensions/number.extension.js b/js/extensions/number.extension.js
index 0e32bb8595ea16d40ec06091506ee072e281a015..4100d71828586408ac09ad1d87ade1bd922d709a 100644
--- a/js/extensions/number.extension.js
+++ b/js/extensions/number.extension.js
@@ -1,9 +1,3 @@
-/**
- * Checks if the number is between two given values.
- * @param {number} min The minimum value.
- * @param {number} max The maximum value.
- * @param {boolean} inclusive Whether or not to include the minimum and maximum values.
- */
- Number.prototype.between = function(min, max, inclusive = false) {
+Number.prototype.isBetween = function(min, max, inclusive = false) {
 	return inclusive ? this >= min && this <= max : this > min && this < max;
 };
diff --git a/src/Mods/SecExp/js/secExpBC.js b/src/Mods/SecExp/js/secExpBC.js
index d7707ad795708962d0cbaf50196f435df195a11a..cd64d30599ab68d3ab4f743296aa45562f9a6eea 100644
--- a/src/Mods/SecExp/js/secExpBC.js
+++ b/src/Mods/SecExp/js/secExpBC.js
@@ -40,7 +40,7 @@ App.SecExp.generalBC = function() {
 	V.SecExp.edicts.SFSupportLevel = V.SecExp.edicts.SFSupportLevel || V.SFSupportLevel || 0;
 	V.SecExp.edicts.limitImmigration = V.SecExp.edicts.limitImmigration || V.limitImmigration || 0;
 	V.SecExp.edicts.openBorders = V.SecExp.edicts.openBorders || V.openBorders || 0;
-	V.SecExp.edicts.weaponsLaw = V.weaponsLaw || V.SecExp.edicts.weaponsLaw.between(0, 3, true) ? V.SecExp.edicts.weaponsLaw : 3;
+	V.SecExp.edicts.weaponsLaw = V.weaponsLaw || V.SecExp.edicts.weaponsLaw.isBetween(0, 3, true) ? V.SecExp.edicts.weaponsLaw : 3;
 
 	V.SecExp.edicts.defense.soldierWages = V.SecExp.edicts.defense.soldierWages || V.soldierWages || 1;
 	V.SecExp.edicts.defense.slavesOfficers = V.SecExp.edicts.defense.slavesOfficers || V.slavesOfficers || 0;
diff --git a/src/Mods/SpecialForce/SpecialForce.js b/src/Mods/SpecialForce/SpecialForce.js
index bb73ec95b6b1f3f3ae29a4f776d8f6860248afbd..e736864af8311eefd84f18295e113230bd948d9b 100644
--- a/src/Mods/SpecialForce/SpecialForce.js
+++ b/src/Mods/SpecialForce/SpecialForce.js
@@ -1393,7 +1393,7 @@ App.SF.AAR = function(endWeekCall = 1) {
 			upkeep *= 0.75 + (V.SF.ArmySize/10000);
 		}
 
-		if (V.economy.between(33, 100)) {
+		if (V.economy.isBetween(33, 100)) {
 			let multiplier = (1.75 * Math.sqrt(Math.trunc(100000/V.economy-1000)/10)) + (0.2 * (Math.trunc(100000/V.economy-1000)/10));
 			income *= (1 + multiplier/100);
 		} else if (V.economy <= 33) { // There comes a point where a worse global economy no longer benefits your Special Forces.
diff --git a/src/endWeek/saServeYourOtherSlaves.js b/src/endWeek/saServeYourOtherSlaves.js
index e7bc6922dfd575c133376d0400f92fcff8d90371..974f646cf6142796e82b4b9f88389aef4fed30a7 100644
--- a/src/endWeek/saServeYourOtherSlaves.js
+++ b/src/endWeek/saServeYourOtherSlaves.js
@@ -1456,7 +1456,7 @@ App.SlaveAssignment.serveYourOtherSlaves = (function() {
 				if (slave.fetishStrength < 100) {
 					slave.fetishStrength++;
 				}
-			} else if (fetishChange > jsRandom(0, 100) && slave.fetish !== "masochist" && slave.fetish !== "submissive" && App.EndWeek.saVars.subSlaveRatio.between(0, 0.8)) {
+			} else if (fetishChange > jsRandom(0, 100) && slave.fetish !== "masochist" && slave.fetish !== "submissive" && App.EndWeek.saVars.subSlaveRatio.isBetween(0, 0.8)) {
 				r.push(`Being used as much as ${he} is starts to take a toll on ${him} sexuality; <span class="lightcoral">${he} begins to enjoy being your chattel's fucktoy.</span>`);
 				slave.fetish = "submissive";
 				slave.fetishStrength = 65;
diff --git a/src/js/rulesAssistant.js b/src/js/rulesAssistant.js
index 6e17200a3e2866b122551dba0174b2a11a1b4c30..594eb44f3d735b35ac6354a84229a5ae2794d132 100644
--- a/src/js/rulesAssistant.js
+++ b/src/js/rulesAssistant.js
@@ -142,7 +142,7 @@ globalThis.ruleAppliesP = function(rule, slave) {
 						slave
 					);
 			}
-			flag = slaveAttribute.between(cond.data.value[0], cond.data.value[1]);
+			flag = slaveAttribute.isBetween(cond.data.value[0], cond.data.value[1]);
 			if (cond.applyRuleOnce && flag) {
 				V.rulesToApplyOnce[rule.ID].push(slave.ID);
 			}
diff --git a/src/js/rulesAssistantOptions.js b/src/js/rulesAssistantOptions.js
index fb71848936cabb24564abfbc82ecdb73414d3aab..0e3f68cc364adb912b79dd9aefdea6f4c2fac93f 100644
--- a/src/js/rulesAssistantOptions.js
+++ b/src/js/rulesAssistantOptions.js
@@ -1386,7 +1386,7 @@ App.RA.options = (function() {
 				current_rule.condition.function = "custom";
 				current_rule.condition.data = "";
 				this.show_custom_editor(CustomEditor, current_rule.condition.data);
-			} else if (this.betweenP(value)) {
+			} else if (this.isBetweenP(value)) {
 				current_rule.condition.function = "between";
 				current_rule.condition.data = {attribute: value, value: [null, null]};
 				this.show_custom_editor(RangeEditor, current_rule.condition.function, current_rule.condition.data);
diff --git a/src/js/slaveCostJS.js b/src/js/slaveCostJS.js
index 7a48568209890b4756e79d694830581629493585..778d7f550bdff8e9eb1c1fd130d985616c0da4d1 100644
--- a/src/js/slaveCostJS.js
+++ b/src/js/slaveCostJS.js
@@ -433,7 +433,7 @@ globalThis.BeautyArray = (function() {
 				adjustBeauty("Age: Youth Preferentialist", ((30 - slave.visualAge) / (30 - V.minimumSlaveAge) * ((arcology.FSYouthPreferentialist / 2) + (arcology.FSYouthPreferentialistLaw * 10)))); /* max 60 */
 			}
 		} else if (arcology.FSMaturityPreferentialist !== "unset") {
-			if (V.retirementAge.between(30, 60, true)) {
+			if (V.retirementAge.isBetween(30, 60, true)) {
 				adjustBeauty("Age: Maturity Preferentialist", ((30 - slave.visualAge) / (30 - V.retirementAge) * ((arcology.FSMaturityPreferentialist / 2) + (arcology.FSMaturityPreferentialistLaw * 10)))); /* max 60, problems if retirementAge is 30 or under */
 			}
 		}
diff --git a/src/pregmod/eliteBreedingExam.js b/src/pregmod/eliteBreedingExam.js
index 7ef0e5206425db390bd0c17eaceda92ec10e2068..bc5ebdf955f4c8cca87f01984512433cd14e6839 100644
--- a/src/pregmod/eliteBreedingExam.js
+++ b/src/pregmod/eliteBreedingExam.js
@@ -199,7 +199,7 @@ globalThis.eliteBreedingExam = function(slave = null) {
 			}
 			r.push(`Must not be overweight. ${result()}`);
 			if (slave) {
-				test = slave.muscles.between(musclesMin, musclesMax);
+				test = slave.muscles.isBetween(musclesMin, musclesMax);
 				fixable = (slave.muscles <= musclesMin && slave.muscles > musclesMax - musclesMin) || (slave.muscles >= musclesMax && slave.muscles < musclesMin + 30);
 				if (fixable && passing === 0) {
 					passing = 2;