Place the Watch-Body into the Case.
Position the Ring on top of the Case and Watch-Body, so that the heels of the Ring fit into the cuts of the Case.
Press the Ring lightly downwards and turn in clockwise direction. You will hear a calming “click“ when the assembly is secured.
(Turn counter-clockwise to release the Ring.)
To change the strap: push the pin on the bottom of the watchband towards the center. Thereby you can connect or disconnect the strap from the lugs of the case.