To be used in conjunction with the 315mm Inspection Chamber Base (B3150), this underground inspection chamber riser is 315mm diameter and 185mm in height. Risers are used for extending the chamber depth to your required size, you can stack them or they can be cut to the size you need which you can do with a standard fine-toothed saw. This riser has a built in seal and you should always ensure when installing risers that the integral rubber seal is located to the bottom groove of the riser.