The Multi-Ref is not a test device as such, but the tool I use to test my test equipment. I got the idea for this from the user [matseng] as the Dangerousprototypes.com forum, and found it very useful. MrRef, as it was called, is just two coin cells powering a precision voltage reference. The intention is to allow checking your own multimeters for accuracy and drift. Not everybody has a 6.5 or better DMM at home, with a accuracy of 0.01% or even better. Back then my best DMM was a TekPower TP40 ...