What is the interchangeable
hand saw system?

There is a specially-designed hand saw system which consists of a handle and several interchangeable blades. 

The handle comes in two sizes: large and medium, and there is also a version available for left-handed users. 

The blades that are part of this system look very similar to regular saw blades, except that where the handle would normally be, there is a design cut into the blade which allows them to fit securely in the handle. There are blades available which can cut through a variety of materials and achieve either a rough or neat finish.

How to insert or remove a blade

Step 1 - Pull lever

On top of the handle is a lever.

To unlock the handle and remove a blade, this lever must be pulled forward.

Step 2 - Insert blade

With the lever in the forward position you can now insert the blade.

You should insert the bottom part of the blade into the handle first. 

Step 3 - Push lever back to original position

Once the blade has been fully inserted into the handle the lever must be pushed back to its original position, in order to lock the blade in place.