The buffer element is disposed on the lateral wall, and {HEAD ~ the lateral side} faces {TAIL ~ the lateral wall} 
faces
The buffer element is disposed on the lateral wall , and { HEAD ~ the lateral side } faces { TAIL ~ the lateral wall }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL