Today I received my Sunset Insert SI1 for my Glock 19 Gen3. It's a back strap plug that allows for storage of a single round, battery, etc. Pros: 1. It's a great idea and has potential, but needs a redesign. 2. Allows for the storage of a single round, which helps me since I always carry RTF. When I want to not carry RTF, all I have to do is remove the chambered round and put it in the plug instead of in my pocket, in a bag, etc. 3. Storage compartment for Torch batteries, single round, etc. Cons: 1. When using it in conjunction with the +2 glock magazine extension, when ejecting the magazine, the extension tends to grab the plug and open the storage compartment. 2. It sits substantially outside of the backstrap detent, even more so than the OEM magazine floor plates...so it will look awkward if that's what you use. 3. Not the greatest construction materials. 4. Lid doesn't "snap" into place. Two small plastic mini dowels hold the lid closed merely by friction... so it can come loose and open. 5. Consistent opening and closing looks like it would cause the unit lid to fail at the pivot point eventually, rendering the device useless. Bottom line? I would not recommend it unless you use Pearce grip extensions EXCLUSIVELY.