I’m assuming you aren’t in the US because you said it’s winter there, but here’s the one I got, just so you can get an idea of what I am talking about.
Mighty Paw Hands Free Dog Leash |... https://www.amazon.com/dp/B00UZXPM00?ref=ppx_pop_mob_ap_share
I bought the 36" Mighty Paw version of that leash: http://www.amazon.com/Mighty-Paw-Premium-Lightweight-Reflective/dp/B00UZXPM00/ and it doesn't seem it up close, but the reflective thread is quite reflective.
The Mighty Paw leash (and probably ht one you linked) is elastic inside of a webbing tunnel, and I gather all of the excess webbing sheath right next to the belt and then just hold it bunched up with my hand/fingers and then the dog can't get any stretch out of the elastic unless I release the webbing.
It is nice for running, but also walking because then my hands don't get cold holding the leash.