Does anyone know what this is?

it would be good to add some pest management onto the corflute.

Something like this as an oil catchment. You can put a bead of silicone on the corflute slider to create a lip, so that you can use this as a catchment when in the bottom slot, and flip it upside down so it still fits into the top slot. Best to have the pest in your base than in the hive. –Kieran