MKS 19400 Two-Prong Watch Case Opener (Side Opener) for Screw-Backs | Meikosha, Made in Japan

Original watchmaker's tool by MKS (Meikosha) from Nagoya – not regularly available in Europe (except from us).

The MKS 19400 is the standard tool for screwed case backs in Japanese watchmaking workshops – a tool that is simply considered the "royal road" there: Almost all common screw-down case backs can be opened and closed again with this one opener. Two precisely guided claws with interchangeable inserts engage in the notches of the case back; the knurled screw allows the distance to be set precisely to the case, so that the claws sit snugly and without play.

The forged metal body transmits the torque directly and controllably – tightly seated case backs, where lighter openers might slip, can be easily loosened. In combination with a case holder (e.g., the MKS holder from our Battery Change Tool Set), opening and closing becomes even more comfortable: clamp the watch, position the opener, and have both hands free for controlled rotation.

For large cases with backs around 50 mm in diameter, MKS offers its own large version – please contact us if required.

What distinguishes the tool from European counterparts:

The three-point openers common in Europe, based on the Jaxa design, distribute force over three claws – which sounds stable in theory, but in practice means that all three points must grip exactly simultaneously. If one claw does not sit perfectly, the tool slips. The MKS two-claw opener works on the opposing principle: Two precisely opposite claws with parallel guidance that can be precisely adjusted to the notches and self-center under load. From our own workshop practice, we can say: In terms of fit accuracy, power transmission, and scratch safety, this opener is clearly superior to Western counterparts – not without reason, the Japanese watch industry has been working with this design for decades. The interchangeable claw inserts are also available individually, so the tool is designed for life. Comparable Swiss quality (such as the Bergeon 5700 with accessories) costs many times more; simple Jaxa wrenches do not achieve the precision of the MKS guide.

Reference:
MKS 19400 (Catalog No. F20260)

Condition:
New product, original packaging

Note
Improper use of tools can damage watches. Use is at your own risk.