measuring poly thin skin base

Hi can someone please tell me if the uts stretches to the size you want or should you cut it exactly to size? My temples from point to point measures 6 inches and from front hairline to back of balding area is 9 inches so would I cut the base to that size or a little smaller and stretch it to the size I need? if so how much smaller? thank you

Ideally get it exact/close or slightly bigger then cut down. UTS is fragile so I don't think stretch will be good.