When I have equipment, I really need to know some things:
How big is it?
I need dimensions. Length, Width, Height. Diameter if it's circular.
I need to know how much internal space there is for holding things, too. Volume, yes, but dimensions, too. "Holds 6 cubic feet" is great, but It's easier for me if it's 3 x 2 x 1 so I can say no when someone tries to stick in a 5' tall item.
How tough is it?
HP, DR, and HT.
How much it weigh?
I also need this for animals, monsters, people, etc. They are going to get picked up and hauled around. My players are going to want to make it into a Zombie, sell it for parts in town, use it as a barricade, etc. Size Modifier is critical, but I need weight, too.
How much does it cost?
Usually included, but very important. It's going to get sold or bought, eventually. How much does it bring or take?
How long does it take?
How long does it take to put on or take off? Time might be critical, and I might not really have unlimited non-combat time to just have it work.
What game effects does it have?
I need to know what it does when it gets used.
I'm going to keep this list handy when I write my own specific pieces of gear, and make rulings on the above on existing pieces.