Not very consistent out of the box. I suspect the o-ring or spring needs a better size. Modified shaft with a softer O-ring and additional ventilation openings. Works a little faster and a little more stable. Now remember that my review is not biased. I have not tried more expensive versions of well-known brands. Overall they work flawlessly and apart from being 90% vented and unwinding with a handheld meter it's not a big deal.