Product review (4 stars): Design Superior to 'Square Box' Diverter. But Treat It Gently.
For a number of years, I've had the 'Square Box' dryer vent diverter (also sold by Amazon, Ace Harware and Home Depot). The square type often fell apart when the lint screen was removed for cleaning. The diverter flap hasn't worked for some time.

Yes, the Dunda Jafine model is a definite improvement, although the construction remains too fragile IMO. I would gladly pay a small premium for a more solid unit.

Also, while the lint screen is very easy to remove, it also very course and will likely dump a fair amount dust back into your basement or utility room -- I plan to experiment with placing a nylon stocking over the screen.

I also used metal clamps rather than the nylon tie wraps provided. I managed to fastened the diverter to the basement wall with a set of 3M Velcro-like fastening strips. The fastener adhesive would not stick to the concrete wall so I used Gorilla glue for the one strip.

Treat this unit gently when flipping the flap back an forth. Make sure that no lint is blocking the movement (I think that's what did in my old diverter). It's a always good idea to clean it with each load of clothes just as you would the dryer lint screen.
Will provide an update in a few months if anything changes.

UPDATE 18 MONTHS LATER -- I had to replace the unit as the small trap door on the flap had become detached and lost. This meant that some warm air would come back into the basement in the 'Summer' setting. This validates my original review: a well designed product but please couldn't it be beefed up to be more durable?