This pocket knife pattern is very popular and highly sought after among collectors.  They go by the name sunfish, elephant toenail or just toenail knife.  These knives are extremely beefy and were meant for rough and tough use.  The master blade is super thick and wide and usually features two pulls (a nail nick and long pull).  They usually feature a large secondary pen blade as well.  Some of the most collectible sunfish patterns were made by Case, Cattaraugus and Hibbard, Spencer, Bartlett & Co.  If you find an oldie in good shape, you have a great knife!  I appreciate any traffic from these links as I earn a commission at no extra cost to you.