This is an example of a small slide rule designed to be carried in one's pocket. It measures about six inches in length and is constructed of moulded plastic. This particular one was a promotional giveaway from Asco Valves.
The scales on the front are (from top to bottom) A, B, CI, C, D, and K. The B, CI, and C scales are carried on the sliding member.
The sliding member may be removed and turned over to reveal S, L, and T
scales (from top to bottom).