These are holste for for 3 of the Eve Home HomeKit enabled devices. These fit the: -Eve Degree -Eve Button -Eve Room I designed it to be just a tad bigger so that it's easy to remove them to change/charge batteries. Has recessed screw holes, or use double sticky tape. Theres two here different surface mounts -flat surface such as a wall -pitched surface such as siding (for example, mounting The Eve Degree on siding)