Coleman Mach 8430A635 ChillGrille Ceiling Assembly, Heat Ready, White adco Once you have this measurement

Once you have this measurement compare it to the height of this shroud which is 12

1x 121-M8UL Thread Sealant 1/2 Wide

It easily mounts directly on RV and is made from durable ABS plastic

Also good for periodic cleaning

Nothing to calibrate

Coleman Mach 8430A635 ChillGrille Ceiling Assembly, Heat Ready, White adco Once you have this measurementAir Conditioner Ceiling Assembly; DELUXE CHILLGrille ; For Use With Coleman Mach Ducted Air Conditioner System; Heat Ready; Lateral In Roof Ducting; Side Air Discharge; White; For Use With Wall Thermostat; With Control Box OMNI DIRECTIONAL louvers are designed to direct conditioned air downwards into the RV Interior in any direction. When the omnidirectional louvers are closed, conditioned air is directed forward and aft through the front and rear air