I will do this post in English to somewhat increase it potential audience. I write it mainly though because like with many things, the next time I need to do it, I will probably have forgotten how I did it this time.
I bought a replacement set of Aqualung Slingshot Straps and Buckles. They use springs and are expected to be more durable than the original ones. However they also look much cooler than the original ones, so I decided to make them my main straps and use the original ones as spares. This comes in handy because the whole family uses Aqualung fins and the all can use the same straps.
Click on any of the images for a larger version.
If you know how to do it, it takes you about 10 minutes to replace them.