This is an OEM rebuild kit for the common modules on Edwards EH 2600, EH4200, QMB 2600 and QMB 4200 booster blower pumps. The common modules are located on either side of the helical rotors. This kit includes the seals, o-rings, bearings and other parts required to overhaul the common modules of your pump. Major and minor rebuild kits for these pumps are also available.