These are the socket holders for the Tool Grid system. You would use these to organize and store your socket sets. These come in packs of 25 (Besides 3/4" which come with 15 pieces in a pack) and in four sizes, 1/4", 3/8", 1/2", 3/4" in Metric (Blue) and SAE (Red). I would order more than you think you need as they're fairly cheap, you're going to be better off having more than you need than not having enough.  I discovered the Tool Grid system while running around SEMA. When I saw it, I knew it was going to change the way I looked at tool organization. Foam is great, but if you replace a tool or get rid of one, you have to redo the drawer with an entirely new piece of foam which is very time consuming. This is where Tool Grid by Mantis comes in. Because the entire system is modular, it's extremely easy to add and take away tools just by swapping a few pieces out. It also improves your ability to lay tools out. Instead of just laying tools flat, it gives you the option of storing tools vertically which opens up a lot more storage space. While Will and Chris were down at my wash-bay demonstrating every aspect of the Tool Grid system, we were able to consolidate two of wrench drawers into one. It really got my mind racing on just how organized and efficient my drawers could be.  1/4" Socket Holder(Metric)-TGH-04PM 1/4" Socket Holder(SAE)-TGH-04PS 3/8" Socket Holder(Metric)-TGH-05PS 3/8" Socket Holder(SAE)-TGH-05PM 1/2" Socket Holder(Metric)-TGH-06PM 1/2" Socket Holder(SAE)-TGH-06PS Vertical Height Dimensions : 1/4" Socket Holder : 3/4" 3/8" Socket Holder : 3/4" 1/2" Socket Holder : 3/4" Vertical Height Dimensions with Mat & Board: 1/4" Socket Holder : 1 1/4" 3/8" Socket Holder : 1 1/4" 1/2" Socket Holder : 1 1/4" FAQ: Toolgrid Parts List Toolgrid Worksheet And Setup Guide Toolgrid Board Setup Guide Toolgrid Proper Installation & Use Instructions Toolgrid Universal Holder TGH-18P and TGH-19P Setup Instructions Identification Label Instructions Toolgrid Container Instructions