Some scrollers (incl. Forerunner (although the
manual says a 7" Forerunner will work on a PAR64 since they never made a 10" version)) are referred to as 10" (10x10), 7" (any 7.5x7.5), and 4" (SourceFour
ERS).
Adapter plates will allow use of larger scrollers for smaller fixtures, but not the other way around, obvs.
@BobHealey, are you looking at
gel shield or
heat shield?
IMO, the best (and most expensive) of either is
Apollo's
Gel Shield. Which I'm inferring from context is that which at you are looking. I don't think the
Wybron Forerunner has a provision for it, so you'll have to get creative. I'd probably affix the prophylactic media between the mounting plate and
scroller body, pre-punching a screwhole in each corner. In this application of application,
Gel Shield is thick, rigid, and tumescent enough so as to not require a frame.
Four 8"x8" cuts ($12.50x4) are less expensive than a 20"x24' sheet ($61.45). Too bad you don't need five or six cuts.
Sorry for the locker room talk, ladies.