The California Competition Works SIX Shell Caddy Tactical Shotshell Ammunition Carrieris made of glass-filled nylon. 

BLACK - 6 SHELL - Universal Belt Mounting also fits Molle systems and any belt up to 55mm.

This carrier comes with two spacers - the thin one is used with U.S. made slugs, the thick one allows 2-3/4" U.S. made buckshot and birdshot. The 4 or 6  round capacity speed stripper will also hold one 20/30-round Ar magazine.  Ideal for 2 / 3 gun use.

Technical Information:  California Competition Works Shell Caddy Tactical Shotshell Ammunition Carrier - 6 Round

Carries: 2-3/4" and 3" Magnum Shells 
Fits Belts up to: 2-1/4" Wide