This is a factory SIG P320 18-round magazine, chambered in .40 S&W and .357 SIG.

It also fits in full-size SIG P250 pistols.

Features:

• Corrosion-resistant, steel construction
• Steel feed lips and anti-tilt follower for reliable feeding
• Front witness hole and side-facing, numbered round indicators at 5, 10, 14, and 18-rounds
• Extended polymer base pad with rugged grip texture
• Made in Italy by Mec-Gar (who manufactures all SIG magazines)