According to Paul G, this grip sleeve was developed by a recently retired HRT officer. Paul also claims that HRT officers are rocking these on their duty Glocks.
Here is a video by Paul G that explains how the Grip Sleeve is designed to work and address some concerns some have raised about the device.
In this photo you can see how your support grip applies pressure forward pressure on the grip sleeve.
The grip sleeve is only $22.95 on Warren Tactical’s website.