hook oil ring 钩形刮油环

ring off the hook 电话响个不停

single-hook ring 鼻形环

ring chain hook 弹簧钩链

double-hook oil ring 双刃刮油环

single-hook piston ring 单钩活塞环

hook-ring for hopples 脚栓钩环

double hook oil ring 双刃刮油环

double-hook piston ring 双抱钩活塞圈