Steel bushed rollerless chains , attachments and sprockets .
工程用钢制套筒链、附件及链轮。
Agricultural , detachable , and pintle chains , attachments , and sprockets .
农用可拆卸和斜栓节链附件和供片轮。
Film perforation : hole punched at regular intervals for the length of film , intended to be engaged by pins , pegs , and sprockets as the film is transported through the camera , projector , or other equipment .
