What is the purpose of the screw back of a watch? What is a screw opener?

When I saw the back of the watch, I thought, "This back is so cool!!"

Have you ever seen a back cover like that?

Those who know about it will of course know that it's a screw back! But those who don't know about it may wonder why there is a normal back cover and a cool back cover...

Isn't that about it?

So today I will explain about the screw-back case back.

What is a screw back?

First, let's compare the photos below.

Screw-back case back
Screw-back case back
Regular watch back
Screw-back case back: 2nd pattern

Regular back cover

Regular watch back

When comparing these images, the top two images are of the screw-back case back.

Below is the back of a regular watch.
When comparing the two, it's easy to see that the screw back has six square holes.

What is the purpose of the screw back design?

It's not just a cool design, it's a shape with a clear purpose.

First of all, a screw-back is a screw-in type back cover that is highly waterproof and airtight, and is often used in combination with a gasket.
There may be some words here that you don't understand, so let me explain them.

Difference between normal and screw-down case backs

Normal back covers are designed to fit perfectly with the frame of the watch from the design stage, so you can remove it by inserting a flathead screwdriver into the gap between the frame and the back cover. This is just one example, so please do not try to open it yourself.

So what is the principle behind the screw back? This is where the screw-in method comes in.

As the name suggests, the screw-in type has threads on the back cover and frame that you turn to tighten the cover. Direction to turn the screw back
Direction to turn the screw backThe back cover can be turned like this.

So what are the six square holes used for?

This will be the hole for hanging it when turning.

There are also special tools, such as screw openers, that are used to remove screw backs. Screw opener

Screw opener

I hope now you understand why screw backs are so airtight and secure.

There are various methods for sealing screw backs, but the method using a gasket boasts the highest level of airtightness.

In this case, you can open it without using a screw opener as long as you can find a way to open it, but this can cause the threads to be stripped or scratched, so it's best to use a screw opener even if you don't plan on opening it yourself.