The BG921HAK P2 is a high altitude conversion kit for BG921(Multi-Speed Blower) models that are field converted to use propane. It works with all 45000, 70000, 90000, and 110000 input btu models of that series. It includes all needed parts for the following application.

It is designed for high altitude, propane (LP) applications ranging from 7501-10000 ft feet above sea level.

This kit includes: 

11J10(Pressure Switch Kit -0.55") high altitude pressure switch 

BG11K45 high altitude propane conversion kit (low pressure switches are included with all Blueridge LP conversion kits for additional piece of mind and to protect your investment)