This compressor pumps air by hand it comes with pressure relief valve the bolt up pattern is 2 x 5 7/8". It was on a Keene ke 200 pump. I have personally never used this item but the man that I bought this pump from said that it worked good. The tag on the side says it is a "Johnson service company pump compressor division Milwaukee WI made in the USA U.S. pat. 2536995 serial no. MH-1 model 152M Johnson compressors". It has a 1/4 pipe tread output fro the hose and its intake is on the top. It is sold as is with no guarentee.