I work in a pulp mill and this tool comes in very handy when sizing up pipes in the field. The calipers quickly measure outside diameters of any round object up to 16 inches in diameter. The gauge is marked with actual inch diameter and also standard iron pipe sizes. When opened completely it also doubles 14″ ruler. Folded, the rule easily fits in your pocket. For years I used PI tapes but this is much quicker and easier to use on pipes in hard to reach or tight spots — you only need access to a small section of the pipe to get a read, not wrap the tape all the way around. Simple one handed operation, great when you are on a ladder. They are available in plastic or aluminum, I prefer the durability of the aluminum, it is worth the extra few dollars.
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