You can find the Mec-Gar 18 Round 9mm Magazine for Glock 19 here.

The Mec-Gar 18 Round 9mm Magazine for Glock 19 Gen1-5 has a heat-treated carbon steel body instead of the standard Glock metal/polymer body, which is thinner, thus allowing for more ammunition. Originally designed for the Glock 17, this magazine has a shrouded high-impact polymer floor plate that matches the grip of the Glock 19 and extends down past a normal 15-round Glock 19 magazine. Unlike other metal magazines for Glocks, the Mec-Gar Magazine was designed for use with the standard polymer Glock Magazine Catch. The magazine has a High-visibility Green, High-impact polymer follower and a high-tensile music wire spring for long-lasting service. Like Glock OEM magazines, the Mec-Gar 18-round magazine also has round count holes on the back.

Firearm: Glock 19 Gen1-5. NOT COMPATIBLE with the Glock 19X.
Caliber: 9mm
Capacity: 18 rounds
Color: Black Anti-Friction Coating