British Standard Chain Duplex per FOOT

British Standard Duplex Chain (Double Strand) 

How to identify your chain ................ The main dimensions of a roller chain are the following, The pitch, the roller diameter and the inside width. First we must identify the pitch, the pitch is the distance between the centres of two consecutive pins of the chain. The inside width is the distance between the two opposite inner sides of the inner link plates and the roller diameter is the dimension of the outside diameter of the chain roller