The standard square sizes are 3/8” by 3/8” varying from 1. However, different cage nuts have different threads with most common variations being M5, M6, 10-32, and 12-24. 10-32 and M5 are similar. Server racks are essential for maintaining an organized, efficient, and scalable IT environment, especially in data centers and server rooms. Server racks are measured in “rack units” (U), where 1U equals 1. Rack cabinets that meet EIA-310 standards have an alternating pattern of three holes per rack unit. 11" thick, which makes them strong enough to support virtually any equipment.