It's bag salt. They seem to like it better than the salt blocks so for the last 5 years thats what I use. They'll dig a hole 12" deep in the ground and come to it all season. We usually put a bag out right before spring and again around 1st of August. I'm not sure why but happens every time, we'll put it out and they'll be so skiddish about coming up to it, usually about 2 or 3 visits before they actually start hitting it. Once they do, it's on, they visit it 3-4 times a day. This brand is what my co-op carries but bag salt is bag salt. I pay around $4 a bag.