Hi Clifford,
The top of the shield sits flush and outside with the white strip outer-most.
The shield then, halfway down, diverts to the inside [ at the cut point], and the flaps
are on the outside. Originally, black goo was used to keep the
flaps in place, use small bits of duct tape, or similar, to secure.
Hope that's clear!
No info on trimmers, sorry.
Regards
Nigel