Fibrous casings are great for bologna, summer and salami. The 1 1/2 x 12 Mahogany fibrous are nice for one pound sausages that hang and cook well in small smokers and ovens. Be sure and soak well in clean water for 20 to 30 minutes before you stuff. Soaking lets the casing expand when stuffing so you get a nice firm sausage when finished. 
a good USA Casing for a good delivered price.