{HEAD ~ The hard disk drive} in the cartridge is of {TAIL ~ a form factor} smaller than that of the disk drive which it replaces 
is of
{ HEAD ~ The hard disk drive } in the cartridge is of { TAIL ~ a form factor } smaller than that of the disk drive which it replaces
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH