including d1 a receiving portion 210 for accommodating the electrical connector d2 a recess 221 for holding a first bolt d3 a compressing board portion 230 d4 a recess 241 for holding a second bolt and d5 a protruded leg portion 250 the five portions are respectively described as follows the receiving portion 210 is open through from the front surface to the back surface and is formed between the top end 201 and the bottom end 202 of the connector housing 200 the accommodating space of receiving portion 210 approximately matches with the volume of the electrical connector 10 so as to accommodate the electrical connector 10 therein the receiving portion 221 is formed on a lateral side of the receiving portion 210 to vertically extend from the top end 201 toward the bottom end 202 the accommodating space of the receiving portion 221 approximately matched the diameter of the bolt 113 so as to accommodate the bolt 113 therein the compressing board portion 230 is formed on the top end 201 of the connector housing 200 and is adjacent to upper parts of the receiving portions 210 and 221 when the compressing board portion 230 is pressed down by pressure the receiving portion 210 is slightly deformed to diminish the recess 241 is formed in the compressing board portion 230 of the connector housing 200 and is located right on top of the receiving portion 221 and an inner diameter of the recess 241 is designed to match with an outer diameter of the bolt 130 so that the bolt 130 can pass through.