Based on this product's specifications, here are some alternatives and similar models
Inspection Chamber Cover MAXPOL System 300×300 mm, brown
Summary description:
MAXPOL System inspection chamber cover sized 300×300 mm in brown. Designed as a removable access cover for utility, drainage or inspection chambers, it provides a finished opening with load-bearing edges and secure fit. Suitable for installation in walkways, yards or service areas where a compact 300×300 mm access point is required.