Well, I look at the T rating in particular. If it's anything around, say a 3 or 3.5, you may need a stepstool, a grabber, or a car to climb up on. If it's a 4 to 4.5 you may need a midsized ladder or a long pole. If it's a 5, you might need a 40 ft pole, a kayak, 32 ft extension ladder, rope/harness, all of the above...or even a helicopter. The D rating could be simple as a pen or tweezers or more complex like a magnet, endoscope, screwdriver, pliers, pipe wrench, batteries, mirror, UV, a fully-stocked travel backpack for long travel, duct tape, wire, or even gear such as gloves, chest waders or hiking boots. This is not everything I've seen listed as a "TOTT," or even all the TOTTs in my truck right now I'm sure, but this should give you the general idea of the variance out there!