Noup, its a vanilla item, very rare in Horizons. I just added stuff to chests cause I tought it would be wrong to have them empty. Its just a little extra touch and not needed at all for the main mechanic of the mod.

Oh, okay. I haven't come across any of those yet. Are they added by this mod?

Ye, they have random stuff. Tho you would need to unlock those with a lockpick.

Could end up being a handy mod. Is there anything to the chests?