The Seiko S-261 is a professional class watch case opener for watch with snap on case backs. This tool lets you easily open snap on watch backs easily and safely, without the risk of scratching. The main feature, and advantage, of this opener is that it holds the watch in a vise and opens with the blade in an all-in-one unit.


Step 1

Insert the four posts into the appropriate post holes according the size of you watch case. There are four posts with nylon tips to help hold the watch without scratching or marring the case. Two additional posts are supplied with the tool and stored in the back of the unit.

Step 2

Place the watch on the case vise with the face down and the case back notch (if there is one) facing the blade. You can rotate the base to help line up the case back notch with the opening blade. Tighten the case vise to secure with watch with the knob (A) on the front of the tool.

Step 3

Tighten the whole vise’s position with the knob (B) on the back of the unit. This prevents the watch from turning while you are trying to open. Then turn the blade holder knob to position the opening blade so it touches between the watch case and the back.

Step 4

Gradually turn the blade holder knob (C) until the opening blade is inserted between the case and the case back. This should only take a maximum of two turns.

Step 5

You can tighten the blade against the watch back until it opens or gently twist the opening blade holder to pry up the case back and open the watch.


The back is now opened. You can swivel the whole opening unit to the side for easy removal of the watch from the vise.

How to Change the Opener Blade

To change the opening blade turn the blade chuck nut counter clockwise to release the tension, then take the blade out.

Remove the spare blade from the vise unit, locate the blade direction, set the blade into the head and tighten the chuck nut.