A blower with {HEAD ~ a filter} is mounted on the outside of the desk and blows clean air into {TAIL ~ the compartment} 
A blower with { HEAD ~ a filter } is mounted on the outside of the desk and blows clean air into { TAIL ~ the compartment }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL