Round 12in Manhole Cover and Frame,10.4in Clear Opening Size,FRP Recessed Solid Top Cover, Replacement Septic Tank Cover and Base for yard,Reinforced Sewage Basin Cover ?Upgraded Non-breakable Fiberglass? This thermoset composite plastic material is widely used in building materials. Our reinforced steel manhole covers has anti-corrosion, lightweight and sturdy properties that can work for many years ?Size recommendations? The manhole frame size is 15.75 in, the solid cover size is 11.9 in, the hole clear opening size need to be 10.45in or less, please ensure that the manhole cover'size match the requirements of the installation ?Non-slip Cover and Base Set? This round sewage basin cover and frame installs uses the recessed method and the set with base makes it easier to be leveled. This cross panel cover is anti-slip when you use it on pavement ?Affordable Outdoor Basin Cover?Reinforced steel in our cover that can load up to 1.5t and embedded install on the ground. Kids can feel free to bike on our sturdy Sump Basin Cover lid in your yard anywhere, lawn, garden, pavement etc