I also thought at first about the extra spring. It rotates helps to keep roll to measure. Especially spring coin can be a key ring.
Sorry to have to pull your links there livan, but they are in violation of our forum policies on advertising.We have a Crowd Sourcing subscription available if you would like to advertise your kickstarter.It is found under your profile/actions/paid subscriptions.:cheers:This is not my kickstarter, these are unfamiliar to me guys, I think about it, I think after visiting this site, although there is a possibility of parallel design ......