Absolutely, we used to help a rancher yearly trail his cattle down from mountain grazing on horseback 17+ miles, then later 13 miles down a secondary highway from the beet fields to his pasture and I had the chemical hand warmers in my gloves and also in the toe of each boot. There's very little cab heat off the back of a horse at 10°. :laugh2:I swear by these. They last about 6-8 hours and allow me to wear thin gloves for dexterity around instruments.
About $1/pair unless you find them on sale though...I used to buy them myself and catch flack from all the crews for being a wuss.