DIN standard design for use with a retaining pin and ring. Chrome molybdenum for use with power tools. Black phosphate finish for easy identification as an impact socket. Designed and manufactured to DIN3129. Ring and pin fixing hole on the female end to secure the socket. Retaining ring and pin included in the set. Supplied in Teng Tools hard wearing case with distinctive branding. Sockets clearly laid out to easily identify which size belongs where.