Kona released their Horseshoe brake booster in 1992 and installed them on their full range of mountain bikes that year.
While we are sure there was some benefit to the brake booster, the Kona frames already featured extra-strong double tapered seat stays, so any increase is braking power would have been minimal. This is probably why Kona abandoned the Horseshoe after only one year.
The Horseshoe is attached to the rear brake by replacing the original brake mounting bolts with longer bolts to accommodate the brake booster as well.
Weight: 131g (97g + 34g of mounting hardware)