The Wixey digital gauges are nice and compact, reasonably priced. Some of the specialty tool places sell a "V" attachment holder for around 65 bucks. I made this out of floor sweepings. I use it in my V block attachment on my lathe for fish mouthing tubing. I can also use it in my tubing bender. I have a commercial type but it is for much larger diameter tubing. This one holds down to 5/8", which is the smallest diameter I cope in my lathe. Home made tools are the best.