This is the Glock 17 9mm 19-round Gen 5 extended magazine. 

Have you been searching for a factory magazine that delivers additional capacity for your Glock 17? If so, look no further!

Constructed from impact-resistant polymer and featuring a hardened steel insert, this magazine delivers superior durability. Inside, you’ll find a high-visibility anti-tilt polymer that keeps each round perfectly aligned and feeding flawlessly.

Last but certainly not least, the rear-facing witness holes allow you to keep track of your remaining rounds with ease! Whether you carry your Glock 17 or compete with it, this magazine is up to the task!

These are sure to sell quickly, so grab a few while you can!