The Seiko Model S-14 Tool is designed to open Seiko monocoque-style (one piece) cases that open from the crystal. This is a complete tool with all 11 spacer rings ranging from 14.5mm to 31mm and all 6 dies ranging from 14.5mm to 24.5mm. This tool also comes with the original box and instruction manual in Japanese. An English copy of the manual can be found at Plus 9 Time.