Graden floor drain cover 138mm x 138mm x 11mm

I have a floor drain, basementstairs coming from the garden. Often found little babyfrogs down there and was wondering, where they came from. Some day i saw them coming through the floor drain. I didn't want to step on a babyfrog, so i made a "frogsafe" cover that stops the frogs from coming up.
Size: 138mm x 138mm x 11mm with 5mm holes. Works perfect.