Received in just a few days. Purchased three sets for three Mags. Yes they work well for one extra round. When adding a plus one finger extension to make eight, hard to add that extra round. Tried with no Mag Guts kit and only the plus one extension with original Glock spring and follower and got one round extra. Does not work with plus one and Mag Guts kit.together, I was able to load eight rounds with both kits on the mag but only with brute force, using a mechanical mag loader. Thing is that if you plan to add a finger extension plus one for your pinky support that cost only $9.95 plus tax no shipping, local store has them.. Or not adding finger extension adding Mag Guts for one round for $17.95 plus tax and shipping. .