You ask and we deliver! Here is a replacement head for your stock magazine, that is already upgraded with our version 2 power tuning spring. This makes upgrading your magazine a breeze! All you have to do is pop out two pins and remove the old head (be careful the ammo spring doesn’t pop out), then simply replace with our new AF Modded T4E Head. This modified valve head will put your marker to about 7.5 Joules depending on type of projectile. **Note There are two different types of heads this one fits the following: TPM1 Smith & Wesson M&P 2.0 Heckler & Koch VP9 Glock 17 Gen 5 *NOT FOR QUICK PIERCING MAGAZINES*