This rearm kit is compatible with model numbers MD2030, MD2030CM, MD2040, and MD2040CM. Use only Mustang Survival rearm kits. Use of other rearm kits may result in improper operation or failure to operate and will void the product's warranty. Regular maintenance can reduce the possibility of inadvertent inflation. For a maintenance schedule, refer to your owner's manual. You should rearm the inflator before the expiry date on the cap passes.This rearm kit contains:One 24-gram CO2 cylinder (threaded)One bobbin (used for automatic mode in A/M models only)One rearming instruction manual