A top housing having a back slot and a front slot parallel with each other, and both stacked on top of a row of lower slots, which is perpendicular to the back and front slots. In this way, the juxtaposition of the back and front slots and the row of lower slots forms two rows of virtual rectangular through-openings. The back of these rows receives a row of first contacts extended through them. The front of these rows receives a row of second contacts extended through them. The through-openings thus guide the contacts at a position of the contacts that is very close to where they contact the lead of the DUT. Hence, there is a very high amount of precision and control of the contact tip that contacts the lead of the DUT.