diff --git a/src/factory/Composites.js b/src/factory/Composites.js
index 0ced474..7612799 100644
--- a/src/factory/Composites.js
+++ b/src/factory/Composites.js
@@ -152,7 +152,7 @@ var Composites = {};
         for (var i = 0; i < number; i++) {
             var separation = 1.9,
                 circle = Bodies.circle(xx + i * (size * separation), yy + length, size, 
-                            { restitution: 1, friction: 0, frictionAir: 0.0001, slop: 0.01 }),
+                            { inertia: 99999, restitution: 1, friction: 0, frictionAir: 0.0001, slop: 0.01 }),
                 constraint = Constraint.create({ pointA: { x: xx + i * (size * separation), y: yy }, bodyB: circle });
 
             Composite.addBody(newtonsCradle, circle);