Sea-Dog Poly Rod Holders offers a great product at a very affordable price, a good option if you're needing to buy in bulk. Designed with a front mount adjustment screw, this allows easy adjustment without having to disassemble the rail mount brackets. A safety line on the rod and or reel is recommended when using rail mount rod holders. Polypropylene. Size: 11-3/4" L x 1-3/4" ID, Fits: 7/8" - 1" Dia.