Quickly find the right socket size even when engraved socket size labels are worn or dirty. That's why we included SAE and metric sizing bolts designed specifically so you can quickly test measure socket size INSIDE the working end. Place the socket on the bolt and see if it fits. If it doesn't, move up or down a size. In a matter of a second, you will know the size of your socket. Note - sizing bolts are designed to help you find the right sized socket, not for storage. They are too short for that and sockets will fall over. Using the low-profile tray in shallow tool drawer is possible since the sockets are stored on their side. Small size but large capacity - Tray measures only 14.6"W x 11"T x 1"H and can holds more than 50 short sockets. Total capacity depends of course on ix and length of sockets. Please measure your drawers before ordering to make sure the tray will fit. Space for other tools – store other tools that you use with your sockets in special spaces. The trays can store sockets with any drive size, but most customers don't mix and use different Socket Organizers for different drive sizes or metric/SAE. Please note that sockets are NOT held in place by clips or magnets in this organizer. The tray is light and portable but sockets will fall out if you turn the organizer upside down. Check out reviews by The Humble Mechanic and The Protool Review to see and hear what experts think!