DC Barrel Plug Seven-Size Gauge Card
A 106 x 30 x 8 mm gauge card for sorting a drawer of unlabeled wall-warts. It has seven through-bores with lead-in chamfers, one for each DC barrel plug sleeve size from 2.5 to 6.3 mm (2.5, 3.0, 3.5, 4.0, 4.75, 5.5 and 6.3 mm OD). Each bore is printed about 0.4 mm over size, so the right plug slides in snugly, rattles in the next size up and won't enter the next size down. Recessed dots under each bore count 1 to 7. A 5.5 mm hang hole lets you keep it in the adapter bin. To tell 5.5x2.1 from 5.5x2.5, use a 2.3 mm drill shank: it fits into the 2.5 mm pin hole of the plug but not the 2.1 mm one.
electronics barrel-jack power-adapter gauge