Roller shutter box e.g. tunnel box, for sealing openings in building to house e.g. carpentry item, has upper face, and integrated checking unit e.g. bubble level, in lower area for checking horizontality of upper face

摘要

The box (10) has an upper face (12), and an integrated checking unit e.g. bubble level (15), provided in a lower area for checking horizontality of the upper face. Verticality of a rear face (13) of the box is verified. A front face of the box and the rear face are bonded together by a top face. The upper face is provided with a set of portions. The bubble level extends on one of front face or rear face parallel to the upper face.