Details
Simply remove the old spring and replace it with this one! All the newer Silver Bullets (from May 2010) come with this spring, so check the spring in your Silver Bullet to see whether or not it is copper in colour. If it is, there is no need to buy one as you already have it!
If you're wondering if you have a hot spring already simply look into the barrel of the Silver Bullet and see if your spring is silver.
If it is, you have the old style spring.