The casing 2, wherein said grasping means comprise downwardly extending {HEAD ~ plate like projections} from said upper casing sidewalls at {TAIL ~ the rear location} of said upper casing 
The casing 2 , wherein said grasping means comprise downwardly extending { HEAD ~ plate like projections } from said upper casing sidewalls at { TAIL ~ the rear location } of said upper casing
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH