the second spacer including a spacer spring, {HEAD ~ a spacer spring insert}, and {TAIL ~ a piston} 
the second spacer including a spacer spring , { HEAD ~ a spacer spring insert } , and { TAIL ~ a piston }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL