Kind of shady... I use a caliper, but it is more accurate if you do three different body parts like the clinics do (tri, peck, ab... or different ones) If I do the "one inch above pelvis" like it says, I can get 2% in front to 8% on the side.
They're good enough for me and the price is right. As far as using 5-site tests...sure they're more accurate but you need a second person to do it for you. I don't use the measurement that it provides...I take 5 measurements at each of the 3 sites and then throw out the high and low readings. Then I plug it into this calculator:
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