The Model-1101 compressor from Thomas Products Div. (formerly Rietschle Thomas), Sheboygan, Wis. (rtpumps.com), uses a rolling diaphragm that combines the best features of both rotary and diaphragm pumps. The ethylenepropylene-rubber diaphragm rolls in a cylinder, generating flows to 3.2 lpm. A motor enclosure and resonator limit noise to 45 dBA. The design increases airflow relative to size and ensures precise flow with few pulsations. The pump is gas tight and can deliver pressures of 7.31 psi. The pump is said to be durable, efficient, and needs no oil for lubrication, making it well suited for medical and laboratory devices.