The RCA22 Series of vacuum artificial horizon are controlled by air driven precision gyros to present the pilot with pitch and roll information. The attractive color scheme of blue sky and brown ground presents a realistic spherical display of flight. Unless other-wise indicated all instruments have a dark blue/brown display, fixed pointer and are unlighted. This is our “Standard” display. All R.C. Allen vacuum gyros run off of 4.5 inch Hg, erect time is 3 min. The 3 3/8” X 3 3/8” x 6” instrument fits in a standard 3 1/8 panel cutout. Weight of unit is 2.75 lbs. A ¼ -18 NPTF nylon tube slip fitting is recommended for vacuum hose installation. A 1/8 – 27 NPTF nylon tube slip fitting is recommended for vacuum gauge installation. : Kelly Manufacturing