disposed on the top surface of the plane portion 402 when the threaded portion 405 of the pin 302 is inserted into the hole not shown the mounting bracket 303 has a mounting portion 412 and a guide 407 the guide 407 is connected to the mounting portion 412 approximately perpendicular to the mounting portion 412 the mounting portion 412 may be integral with the guide 407 the size of the mounting portion 412 is approximately the same as the plane portion 402 of the connector portion 305 thus the mounting portion 412 is tangent to the plane portion 402 when the mounting bracket 303 is movably attached to the connector portion 305 of the brace 301 as explained below the mounting portion 412 has an opening 408 around the center thereof and two projections 409 at both sides of the opening 408 the diameter of the opening 408 is wider than the diameter of the threaded portion 405 of the pin 302 such that the position of the brace 301 is adjustable relative to the mounting bracket 303 after the mounting bracket 303 is installed to the connector portion 305 the projections 409 are approximately perpendicular to the top surface of the mounting portion 412 and disposed around both ends of the mounting portion 412 each of the projection 409 has two hooks 410 at both top side ends thereof the hooks 410 may be integral with the projection 409 fig5 shows an enlarged view of the bracket device when the projections are fully inserted to the rectangular openings of the connector portions fig6 shows an enlarged view of the bracket device when the projections are fully inserted to the rectangular openings of the connector portions and the hooks are bent as shown in.