The ever populare GLOCK Model 17 in Gen 3 trim is arguably the most common variation of the venerable GLOCK lineup. Umarex has the only offically licensed GLOCK replicas on the planet and if your have one of our GLOCK Model 17 Gen 3's in .177 BB, you need to pick up this spare for it so you can practice magazine changes and drill in a more convenient fashion. This magazine holds 18 .177 caliber steel BBs and only fits in the Gen 3 version of this magnificent blowback air pistol.