Best Mineral Block

I just purchased two Katahdin ewe lambs, about 5 months old, two days ago. I have them in a small safe paddock with access to a nice dry stall in the barn, until they get used to things and then I let them go into a larger 3 acre pasture. I put a regular white salt block in the stall, a little hay, although they are definitely not interested in it, a bucket of fresh water of course, and I purchased a bag of premixed lamb feed that I'm just giving them about a cup between the two of them twice a day. They probably don't need any grain, but I want them to associate me with food so that they come to me, at least for food.
I understand that they may also need a mineral block, or loose minerals and I am wondering if there is a specific brand that is best. I hope to be able to just get something from Tractor Supply.

Loose minerals are better for them. Sheep tend to bite the blocks instead of licking them and they can damage their teeth doing that.

Offering minerals salts free choice is a good idea, but don't leave minerals AND plain salt out for them.

You can get a generic sheep mineral from a feed store, just make sure there is no copper. I've been using a mineral mix from Pipestone that has vitamin E and selenium in it.

I use Southern States sheep mineral almost exclusively but I've also used the DuMOR sheep mineral.