I love my Nuttens Bing, but at 6.4 mm I find the button height a tad too high for clenching. A little 400 grit sandpaper takes it down to 5.1mm and the buffing wheel with blue compound polishes it up (at least for me) to a perfect 5.0 mm. The digital calipers are a must and very cheap on eBay at around $7.