7
The Cavity Vertical Extension Sleeve Is Designed To Be Used In Conjunction With The Telescopic Underfloor Vent. Each Extension Sleeve Allows The Vent To Vertically Reach A Further Two Brick Courses And Can Also Be Fitted To The Base Of The Telescopic Underfloor Vent Providing Horizontal Extension. Extends The Vent Vertically To Reach A Further Two Courses Can Be Used On The Base Of The Telescopic Underfloor Vent To Provide Horizontal Extension