Replacement cartridge ball bearing fits the Skyway Tuffwheels® we use on all our trailers. To replace, drive out the old from the inside using a hammer and long punch, then press the new bearing into the hub.
Please note that the outside diameter is just slightly over than 1.375" (=1 3/8") OD in diameter, so it will not fit a 1 3/8" mounting hole. Also, it does not have a flange on its periphery like many bearings.
Here's a video showing how to replace a wheel bearing using a hammer, punch, and two wood blocks:
Inside diameter: .625" / 15.88 mm Outside diameter: 1.378" / 35 mm Thickness: .433" / 11 mm