I have reasonable quality kitchen units, the doors are pretty standard veneered chipboard. Upon testing these after installation, the damper did stop the door from slamming shut, however I noticed that the door sat slightly proud of home when it came to rest, I put this down to the door weight being too light to keep the sping compressed.
I tired mounting the damper a few mmm back from the cupboard egde to no avail, the door slams shut as it did without the damper. I tried various combinations of location and quantities but had no luck.
This product did not work on my kitchen units. I guess you get what you pay for!
Please test somewhere inconspicuous before using these.