The casing body may be provided at {HEAD ~ each} of both sides thereof with a relief which prevents {TAIL ~ the holding or grasping means} from interfering with sliding movement of the slider when the same is slided 
The casing body may be provided at { HEAD ~ each } of both sides thereof with a relief which prevents { TAIL ~ the holding or grasping means } from interfering with sliding movement of the slider when the same is slided
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH