A number of years ago, my son gave me a set of Knee Defenders (really great name!) because he knew I kept getting hit by the rude person in front of me (I have a leg injury). I, OTOH, even on 13+ hour flights - three to four times a year - do not recline because I do not want to affect the person behind me. I have chosen not to use the devices because I felt they were ALMOST as rude as the person reclining without warning. Maybe once out of a hundred times, I have had the passenger in front actually tell me they are getting ready to recline - this was appreciated. If people would just inform, there would be no problem, fewer injuries, and fewer broken laptops - and no need for Knee Defenders.