Review on Greartisan Electric Reduction Centric Diameter Industrial Electrical by Larry Boyd

So, as the name suggests, I bought (and tested) 4 of these in total. They work very well, working 24 hours a day, 7 days a week, at least for the past few days (with 12v, 2 amp power supplies). However, I noticed that the sound from engine to engine is very different. While some are fairly quiet, others are slightly loud to really make noise, with rattling or just loud engine noise. I have about 50/50 (2 quiet, 2 pretty loud). I wish they were all as calm as the calmer ones. One is particularly loud. Not as loud as a shredder or anything, but certainly louder than others.