For example, {HEAD ~ each valve} can include {TAIL ~ a slit opening}, where the slit openings are co linear, or each valve can include a slit opening, where the slit openings are substantially parallel 
For example , { HEAD ~ each valve } can include { TAIL ~ a slit opening } , where the slit openings are co linear , or each valve can include a slit opening , where the slit openings are substantially parallel
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH