My device arrived today and checked it out in the lab. I used a DE-5000 LCR meter (<a data-hook="product-link-linked" class="a-link-normal" href="/DE-5000-Handheld-LCR-Meter-with-accessories/dp/B00S298KJO/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">DE-5000 Handheld LCR Meter with accessories</a>&nbsp;with Kelvin probes (which for some silly reason you have to make and can't buy premade), accurate to around 0.01 ohm, to measure it's DC resistance as I toggled each switch. The first thing I noticed is with the resistance set at 0, all switches off, the actual resistance was actually 0.23 ohm. Flipping the 1 ohm switch actually gave 1.23 ohms, a 23% error. The device is made by putting 28 resistors in series, and a switch to short across each one (off position is shorted). The end result is the resistance of 28 closed switches is 0.23 ohms, which is less than 0.01 per switch, about as expected. The resistors used are 1% tolerance, although due to the series switch resistance, values below 23 ohms will not be within 1%. The 1% tolerance variations will also accumulate, so the overall set resistance may or may not be within 1%. Assuming the resistors were exactly their marked values, setting 23 ohms would give 23 ohms + a bit less than 0.23 ohms series switch resistance, for an error of about 1%.