Stand Up Boot for Mainsheet Ratchet Block. This ensures that your mainsheet block doesn't fall over or hang loosely and risk getting tangled in lines.
The stand up boot works with both the Ronstan Ratchet block or the Harken Ratchet Block. Having your mainsheet get tangled during a race is an easy way to send you to the back of the fleet. One way this can happen is through the mainsheet getting looped around the ratchet block during maneuvres. Prevent this from happening by ensuring the mainsheet block stays constantly upright.