Summary: These were designed by a military member (I think an Air Force Helicopter Mechanic), and was featured on Shark Tank. This is a genius idea. I have been a mechanic all my life, and these are awesome! I keep a black pan in the bottom of my rolling chair, which catches all the tools and spare parts. So I will be adding this to the stack.
Pros: Great fit & finish; the super smooth bottom is very grippy; the yellow color makes it very easy to see parts.
Cons: Cost.
Conclusion: At $40, rating this 4-stars, as there are lots of options available; this is a single tray, but there are multiple tray offerings for the same price.