StarTech M3 Brass Motherboard Standoffs - 15 Pack STANDOFFM3 The Startech.com STANDOFFM3 is the right solution for mounting your motherboard to your AT-style PC Case M3 Brass Motherboard Standoffs - 15 Pack The Startech.com STANDOFFM3 is the right solution for mounting your motherboard to your AT-style PC Case. This pack of 15x M3 Brass standoffs are handy for building any computer systems.