P&H R21143D50 SMARTORQUE VARIABLE FREQUENCY DRIVE (VFD) IN PORR SHAPE T268556

Based on the code R21143D50, this identifies your item as a part of the P&H Smartorque line of Adjustable Frequency Drive Crane Controls. These are heavy-duty industrial units used specifically in crane and hoist operations for precise motor speed control. These units are highly specialized "legacy" automation parts. Because they are often the only thing keeping a 10-ton bridge crane running, their value remains high despite their age.