Squeezing sealant through a Presta valve stem is one way to add Muc-Off Road + Gravel Tubeless Sealant, and pouring it straight into the tire is the other. A free-flowing formula of advanced polymers coats the inside wall of the tire. The synthetic latex sealant suits road, gravel and cyclocross tires. What Our Gearhead(R) Experts Are Saying:"A thorn punched into my tire on a gravel road, and the sealant closed the hole as I rolled. I finished the loop on the same tire."