SELKIRK CORP 104400 4-Inch Support Assembly<div style="text-align: left;"><strong>[Product Information]</strong><br><ul><li>4" inch， 4RV-GVS， Support Assembly， Round， Type B， Gas Vent</li><li>Support Plate should be installed above the joist</li><li>Support plate also serves as a firestop</li><li>Will support a maximum of 60' of gas vent</li><li>RV line of MetalBest round Type B gas vent pipe and fittings is designed for use on approved gas appliances</li></ul></div><img src="http://ecx.images-amazon.com/images/I/3148fRDQQ0L.jpg" noproxy>