This is SSD or 2,5' hdd drive adapter to fit 3,5' bracket in PowerMac. It enhance 2,5' drive bottom holes to fit 3,5' drive bottom holes. For 2,5' drive I choose DIN 965 -> cross recessed countersunk head screws. 3,5, standard flat screws. One version got M3 (ssd) and M4 (3,5) holes. Second version got only M3 holes - that makes M4 screw fit well. M4 screw will make thread in PLA while screwing. But do not overscrew, not to break the thread. Also good for SFF Dell, HP and Lenovo desktops.