Killer innovations glock 17 mag extension - Killer Innovations Velocity Glock 17 Magazine Extension

Overall, a fantastic design! The side of the extension has plenty of room for your thumb and a nice ledge to prevent dropping on fast reloads. Compared to the ZEV which is also has a tool-less design it works great. The design allows you to clean the mag tubes incredibly easy. No Allen key or tool needed to pull out the spring and follower.