Stainless steel hose and tube clamp.  Commonly used in the VW T3 Vanagon to clamp the fuel vapor hoses which run from the fuel tank to the fuel expansion tanks in the front wheel wells. 

Clamping range - 11.5-14.00 mm

This is an Oetiker-style pinch clamp that provides a complete and positive seal.  You'll need a pair of pinch clamp pliers for installation.

Ref ID: 52545K-52