This well worn set of keys came from a retired Union Pacific worker. There are 2 hollow switch keys and a skeleton key. They are all on a ring and have appropriate wear for many years of use. I will describe them as best I can, but I am not an authority so please look at all pictures. Smallest is hollow, 5mm diameter, has the most wear, is stamped and appears to be ADLAKE. 2nd switch key is clearly stamped Slaymaker; and UP???C; 7mm diameter; appears to have more copper in the metal than the others. 3rd is the brass skeleton key; also is stamped ADLAKE which is quite worn off, flip side is stamped UP.