Patio Wheel stamped "168"

i have a single wheel assembly similar to Sliding Door Rollers
81-007 81-024 81-090
the set i have has "168" stamped on the side
The measurement i have are 1 13/16 length - 1/2 wide - 1 1/16 tall - 1 1/8 wheel x 1/4 wide
Can i Mail what i have to you for identification i will need 4 wheel assembly ( 2 sets)as well as other items i have order from you before.