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