Works ok, not reliable enough for edc - FAB Defense OPMOD 4 Round Magazine Extension For Glock 43

There are two different revisions of Glock mags - they work with the first but they only get +2 or +3 capacity with the second. Additionally the stock springs are not reliable with these extensions, so I got extra power springs and gutted the extended spring pieces in these extensions and they now feed reliably. However, it would have been cheaper just to get shield arms magazines in the first place. I've had no reliability issues with those and they have a smaller footprint than these extensions. Unless your EDC is perfectly flat against your body these stick out like a sore thumb.