The Cooper 550 degree Large Thermometer has an easy-to-read 2-inch dial face (total diameter is 2.25 inches) and features an 8-inch stem. You need a good 550 degree thermometer to roast with a stovetop popper or air popper, and referencing temperature to determine your "degree of roast" in any roaster is a plus.
This is all stainless steel, including the dial face, with a glass face cover, and it comes with a stainless clip so you won't have to cobble one. It is easy to re-calibrate by adjusting the nut on the stem (instructions are included -you might want to calibrate it even before its first use, since vibration in shipping can affect the setting). We have a page with ideas about how to make a clip yourself. And Ken David's book Home Coffee Roasting has thermometer ideas too.