I just got Kolstein Heritage strings from Lemur and now its time to put them on. Last string changing was without a string winder, so thought this would make string changing less than torture. So, I have this black plastic Heriba string winder. One part fits nicely over the tuning mechanism, but I was curious about the other part of this. It has a 1/2 inch diameter hole and this part rotates. I can't figure out what the purpose of this is for and it must rotate for some reason. If it was trying to fit a drill bit or something, the fact that it rotates would defeat the purpose. Very humbly thankful for your enlightenment on string winders.