Stop the guesswork!  Only by correctly identifying your fittings can you hope to build a leak-free plumbing system on the first try.  This compact kit is all you need to identify just about any plumbing fitting in the field. 
This pocket-sized set includes a patented measuring caliper with four angle gauges built in, the handy booklet How to Identify Ports and Connectors, a thread pitch gauge with 14 inch and 3 metric sizes, a flexible 3x Fresnel magnifying lens for hard-to-read part numbers, and a vinyl case to keep everything together.  The case measures just 4.5" x 5.5" to fit in almost any pocket or toolbox, so you can carry it with you anywhere.