The eraser includes {HEAD ~ a housing} having a front wall to which is attached {TAIL ~ an eraser head} 
The eraser includes { HEAD ~ a housing } having a front wall to which is attached { TAIL ~ an eraser head }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL