18 size, Keystone, J.Boss, Open Face, Screw Back & Bezel, Case. Gold Filled, 10K, & Warranted to Wear for 20 years. 

1900 to 1910 era, Pendulum & Lever Set Case.

Elk Engraved Back.

Serial Number 8553704. Marked Keystone & J.Boss, 20 yr. The Scales symbol indicates a Gold Filled Case of at least 10K [a Crown over the Scales would indicate a 14K Case] & the Keystone represents the Manufacturers Trade Mark.. This currently holds my Illinois, 18s, 17J, Bunn.