The JWI-1200 and JWI-2400 are JWI Wall Air Inlets that operate on negative pressure that pulls back a frictionless styrofoam baffle to provide direct access of fresh air into your barn. The JWI-1200 and JWI-2400 Inlets open wide when plenty of air is needed, flow adjusts automatically to protect animals during cooler periods. Insulated hinged cover can be closed tight in cold temperatures or adjusted to any degree for proper air distribution. Counterweight allows for fine control.