The raised member 1025, as well as the recess 1030, join with mating portions 1035 and 1040 respectively, of the opto housing 750, as shown particularly in FIG. 11A. In addition, as shown in both FIGS. 11A and 11B, the opto housing includes an angled bore 1045 symmetrical to the bore 1020 for supporting the second of the LEDs 730 which, like the first LED, illuminates the lower portion of the ball