It's been over a year since the Kickstarter funding period ended, and they have yet to deliver anything except false promises and dubious claims. Del Marth LLC was founded by Ehrien Marth, Mike Walton, and Brandon Conant. They have continually pushed back delivery estimates, treated backers very rudely, posted videos that are questionable in terms of demonstrating functionality. They have yet to demonstrate the 500 ft. claim, which is the only feature that makes StoneTether unique. Anybody thinking of purchasing a StoneTether should be very wary.
Bottom Line: No, I would not recommend this to a friend