This attachment is for flat surfaces. Shielding the screw against water, dirt and vandalism. It prevents the device from unscrewing due to the total lack of access to the screw. Available sizes: Ø40 with screw hole M8-M10-M12. They are produced in 4 basic colors - yellow, red, blue, green, but at the customer's request we will make any other color. Material: Polyamide PA6