To ensure compliance with building regulations, a chamber reducing ring is required to be used if the height (or depth) of a 450mm inspection chamber exceeds 1200mm.The reducing ring brings the clear opening size of the chamber down to 350mm, the size permitted for all 450mm chamber installations over a depth of 1200mm and up to a maximum invert depth of 3000mm.The reducing ring clips inside the frame of the manhole cover using a clever snap lock design. It is specifically designed for use with the following chamber covers;CLKS452CLKS456CLKS1657 (not CLKS1657KMB)CLKS450SRCLKS450SR/46SLThis reducing ring, manufactured from recycled polypropylene, is lightweight and easy to install.Please watch our overview video below