Longer lengths to 36 inches can be provided. For automotive under the dash work the 10 inch is preferred. The 15 inch probe is handy for reaching lower engine areas and long narrow access areas such as in appliances and industrial copy machines, etc. You can resharpen by hand using a stone or fine grit abrasive sheet. You can also reset the calibrated length since there is extra needle length essentially stored inside the needle knob.
Instructions show how .
The 'Wire-Tap' can lock onto wires haveng outside diameters between .030 and .250 inches. Comments have been absolutely positive and many professional tech's have said the 'Wire-Tap' turned out to be one of the best tools and timesavers they ever bought.