This is the Great Planes ElectriFly Power System Brushless Motor Mount. This attaches to the firewall and the electric motor attaches to this mount. FEATURES: Direct replacement for the Great Planes GPMG1091 .60-1.20 (10-20cc) glow mount Perfect fit for both 50mm RimFire Outrunner and 36mm Ammo In-runner motors Universal motor mounting bolt pattern insures an easy fit with many brands of motors Lightweight aluminum construction for added durability Unlimited adjustability from 3.5-4.6" (89-117mm) For large motors INCLUDES: One motor support for large motors All assembly hardware REQUIRES: Mounting to the firewall and attaching the motor SPECS: Length: 3.59" (91mm) Width: 3.11" (79mm) Height: 2.17" (55.1mm) Weight: 4.9oz (140g) Mounting hole dimensions: 1.85"x1.85" (46.9x46.9mm) rmb 12-20-06 ir/jxs upst jxs 02/29/12