For quick inside measurements of holes and bores without the need for inside micrometers.
Spring loaded bore anvils
Stainless steel construction
Plastic storage pouch
8.0 to 12.7mm
12.7 to 19mm
19 to 32mm
32 to 54mm
54 to 90mm
90 to 150mm
HOW TO USE TELESCOPIC BORE GAUGES
1. Drop the gauge in the hole on an angle (about 15 degrees) and allow the plungers to expand. Tighten a little by twisting the thimble at the end of the gauge.
2. Start to straighten up while feeling the arc of non contact until it's only a few degrees then guess the center point, not that critical and lever the handle to the square position and then carry on past it.
3. Remove and measure with your micrometers or digital caliper.
It's easier than it sounds, basically you need to firm up the plungers when bigger than the bore, hence tipping it, then allow the bore to push them back in. It you practice on a new bearing or something with a known size you'll know when you have the hang of it. It's a skill worth having and worth the time spent to get it right.