The Adam Hall 3782 is a fixed castor for 4982. The 3782 is 40mm and has a black rubber wheel with black nylon frame with a skid panel. This is small enough for fitting to the edge of the case.
The main features of The Adam Hall 3782 include:
Adam Hall 3782 - Edge Castor 40 mm in Nylon HousingReally easy to fit, only thing I would change would be to have wheels bolted not riveted in so when the bearings go you could press out and replace dead bearings or just buy another set and swap the wheels over.