The sleeve is used to lock the support firmly in place and accepts a setscrew

the dryer only extends from the mounting surface by 4 inches

UltraTech Ramp

the unit requires a rough opening that measures 15-3/8 inches in width by 28-7/8 inches in height by 4-1/4 inches in depth

Nidec US Motors BMU3S2A 3 HP, 15 lb-ft HP, 1800 RPM, 208-230, 460V, 182T Frame Restroom Signs The sleeve is used toFeatures: 40 degree C ambient Item: Brake Motor, Motor Type: Brakemotor, HP: 3 HP, 15 lb ft, Nameplate RPM: 1800, Voltage: 208 230 460, Frame: 182T, Enclosure: Totally Enclosed, Rotation: CW CCW, Hz: 60, Phase: 1, Insulation Class: F, Bearings: Ball, Base: Rigid, Shaft Type: Key, Shaft Number: 1, Shaft Length: 2. 81", Shaft Height: 4. 5", Shaft Dia.: 1. 125", "C" Dim: 21. 5, Thermal Protection: No, Cooling: Fan Cooled.