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