Yaktrax is an ice traction "device" that you slip onto the bottom of your shoe. Can one wear this on Shabbat? Possible concerns:
- boneh - "building". Wearing the device involves stretching a band onto the bottom of your shoe which causes some untwisting of the contraption as well as creating the toothed / ridged coil "grip" on the bottom of the shoe.
- Walking with these ridged / cleated device on snow makes ruts in the snow. On hard ice, it makes a dent, if the ice pack is somewhat loose, it may even crush or break the ice itself forming either ice crumbs or breaking the ice pack forming separate sheets. Perhaps, this is a violation of kore'ah - tearing, or something similar?
- If there is no eruv, would this be considered carrying? While you are attaching it to your shoe, it is not a piece of clothing like a boot, and I don't know if it would fal in the same category as tachshit - jewelry - which is permitted.