In addition, the internal surface of the cylinder and the external surface of {HEAD ~ the piston} are grooved or keyed so as to prevent rotation of the piston inside {TAIL ~ the cylinder}  
In addition , the internal surface of the cylinder and the external surface of { HEAD ~ the piston } are grooved or keyed so as to prevent rotation of the piston inside { TAIL ~ the cylinder }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH