This inspection chamber base has a diameter of 450mm and features a main twinwall channel of 150mm, an additional two 150mm inlets at 90 degrees.This inspection chamber base has a diameter of 450mm and features an open main channel with 150mm Twinwall Rocker Pipes, an additional two Sealed 150mm inlets ( cut as necessary ) at 90 degrees.Cover and Frame not included.andnbsp;Riser not IncludedOur inspection chambers allow access to drain and sewer systems for testing, inspection, maintenance and cleaning. These actions can be performed from the surface and should not require entrance into the chamber itself.andnbsp;KEY FEATURES andamp; BENEFITS OF THIS PRODUCTandnbsp;Quick and simple installationandnbsp;Arrives factory assembled in one pieceandnbsp;Design life of 60 yearsandnbsp;Lightweight and requires no specialist equipment to liftandnbsp;Compatible with most UK twinwall pipe systemsandnbsp;Granular backfill_Complies with EN 13598-2 (2009), SfA7 and Building Regulations Part H1andnbsp;4 x 150mm twinwall inletsandnbsp;andnbsp;To view Turtleand#039;s installation guide for twinwall inspection chambers,andnbsp;click here.