<p>An insertion convexity (11) on the frame (2) of a device (1) is inserted into an opening (101) in a wall (100). The first fastening part (120) of the frame (2) faces the first wall surface (100a) of the wall (100). A first threaded member (22; 22B) inserted through an insertion hole (20a) in the insertion convexity (11) threadably engages a second threaded member (23; 23A; 23B; 23C) on a thread axis line (L1). The rotational position of the second threaded member (23; 23A; 23B; 23C) about the thread axis line (L1) can be brought to a first rotational position (P1) and a second rotational position (P2) by operating the operating part (22; 36) of an operation mechanism (22; 22B; 35) that can be exposed in a first direction (X1) from the frame (2). The wall (100) is directly or indirectly tightened between the first tightening part (120) of the frame (2) and the second tightening part (280; 283) of the second threaded member (23; 23A; 23B; 23C) displaced in the first rotational position (P1).</p>
