This is a factory CZ P-10 F 9mm 21 Round Extended Magazine. It is also compatible with the CZ P-09. 

This genuine CZ magazine provides 21 rounds of 9mm and delivers superior durability and reliability thanks to its stainless-steel body and anti-tilt polymer follower. 

To further improve the durability, the magazine features a corrosion-resistant black finish and a high-quality stainless steel spring. With precision-machined feed lips to top it off, this magazine is made to perform in any scenario it encounters. 

You’ll find numbered witness holes on the back of the magazine that provide a quick and easy visual round count. Once you run out of ammo, the bright orange follower indicates it’s time to reload. 

Even though 21 rounds is a substantial amount for a single pistol magazine, carrying an extra and doubling it wouldn’t hurt! 

You may see these go in and out of stock often, so add a couple to your cart while you can!