<B>SELKIRK CORP 187704 Wall Thimble, 4-Inch Review</b><P>http://tinyurl.com/krqrv3g <P><P> SELKIRK CORP 187704 Wall Thimble, 4-Inch <P>4" 4RV-WT Wall Thimble<P>Adjusts 4-1/8" to 7" to fit wall thickness<P>Round Type B gas vent<P>When installed according to manufacturer specifications, the wall thimble provides the required 1 inch air space to combustibles<P>Tested and listed per UL-441 for installation as type "B" and B-W gas vents to be installed in single and multi-story buildings<P>
