This enables an engineer to test a telephone line by simply clipping {HEAD ~ a crocodile clip} onto the test contact member and {TAIL ~ a wall member} 
onto
This enables an engineer to test a telephone line by simply clipping { HEAD ~ a crocodile clip } onto the test contact member and { TAIL ~ a wall member }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL