Mr Heater's Horizontal Vent Kit F102845 maintains appropriate clearances through combustible construction. This kit is to be used for horizontal venting with Mr Heater MHU45 / MHU75 heaters. A gas vent cap, adjustable wall thimble, 4" elbow, 4" x 36" double wall pipe, two 4" x 24" single wall pipe and a 3" to 4" connector are included. Additional parts may be required to meet local codes.