Zhitaoxun 28 Bolt and Nut Identifier Gauge Nut and Bolt Thread Checker 14 Metric & 14 Standard Ruler with Inches and Centimeters On Both Sides: Amazon.com: Industrial & Scientific
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Bolt Depot - Socket button head, Alloy steel black oxide finish, #4-48 x 1/4 "
GEARWRENCH Bolt Biter 1/4 in. and 3/8 in. Drive SAE/Metric Impact Extraction Socket Set (28-Piece) 84784 - The Home Depot
High Heat Heavy Hex Gauge - Inch & Metric - Bolt Size to 4" and Nut Si
Bolt Identification Guide - First Call Auto Supply