No visible markings, measure 3 1/8" long, 11/16 depth ( where rollers are in) , 1 1/2" height. Rollers are 1 1/2". No company name on door. I'm thinking these are your 81-153 I saw initially on your site, but can't find it again. Looks just like it
Dave Sr. from SWISCO responded:
March 25, 2015
I agree, the 81-153 seems like a good match. The dimensions all line up, just double check your measurements to confirm.