Originally Posted by Wild4umlauts
OK - This is possible. The Kneissl Flexon has a wider power strap than the original Raichle Flexons so it's much harder to remove without cutting it, but it is possible.
To remove the strap without cutting:
1. On the side that has the metal "loop" use a large flat blade screwdriver to "stretch" the slot opening on the rear cuff a bit - you don't need much, but just a bit will provide enough room to slide the metal loop out. The stretching isn't permanent and the shell will return to normal.
2. Slip the strap all way through the slot (including the seam) BEFORE attempting to slide the metal loop out. Once you're up to the metal loop rotate it in the strap so that the narrower side feeds into the slot in the shell first. Note that the strap material will bunch up a bit around the metal loop, but if your screwdriver stretch is still there you'll be good to go.
3. With the narrow side of the metal loop feeding into the slot give a few good yanks on the strap from the other side and it should slip though.
4. Repeat process for the other side.
Luckily the Booster strap will just slide into place and doesn't need all this "fun".
P.S. My experience with this setup is that the Flexon, being a 3-piece design, works very well with the Booster strap on the outside of the plastic tongue. Traditional 2 piece overlap boots that have a tongued liner work better with the Booster placed directly against the liner (this is the recommended position). The Booster in combination with a Flexon with a Thermoflex liner helps the liner and boot stay in contact with the leg all the time even when it's outside on the shell tongue.