Not exactly 1 7/8" or 1.875" or even 48mm which is 0.375mm less than 1 7/8". idk why had the description originally two different unequal dimensions? Wrong description.. I measured the cutout of the hole as well as the diameter of the hole cutter (on the outside of each side of the metal of course) and it was slightly smaller making this a real problem for installing the ones I intended Made eyelets. This was about a millimeter below all the measurements given, which is very frustrating when working to tight measurements. Maybe it has something to do with the 1mm coat of paint on the router that came off when you drilled it? This isn't one anyway accurate description, and if you're installing a 2" socket from Home Depot be prepared for a lot of grinding.