block holder meaning in English

块规夹持器

Production in optical engineering ; lens block holders with inside fitting
光学工程生产.用内配合件的镜片块夹具
Production in optical engineering ; lens block holders with outside fitting
光学工程的生产.带外装配件的透镜片夹具
Brake block holders and brake block keys for composite brake blocks on rail vehicles ; technical specifications
有轨车辆的复合制动装置的制动块夹持器和制动块键.技