Well, let's see:
Fedders Type A sleeve dimensions: 25 7/8" W x 16 3/4" D x 16 3/4" H (Fedders P/N BSA000C) Fedders Type B sleeve dimensions: 27" W x 19 3/4" H x 16 3/4" D (Fedders P/N BSB000C)
From Friedrich WallMaster® Thru-the-wall Air Conditioners brochure: <q>Exact fit for Fedders sleeves. Measures 27"Wx16 3/4"H.</q> Looks like a Fedders Type "A" to me.
Friedrich also has their own sleeve: P/N WSC
27"W x 16 3/4"H x 23" D (with front); minimum extension into room: 7-1/2"; minimum extension outside: 9/16". Through-the-wall finished opening: 27 1/4"W x 17 1/4"HNote: a Friedrich's BAK / Baffle Adapter Kit needed to install your Friedrich Ws12a10e into a sleeve deeper than 16 3/4".