I bought 2 pairs of these, for my son (3yo) and daughter (4yo) before going to Santa Pod to watch Monster Truck action. They arrived before the expected date. They are fully adjusted and even fitted my head! Track side, my kids were not phased by any of the noise once these ear defenders were on. At Santa Pod they send their jet car down the quarter mile and you stand a few meters away from the track. It is exactly like being near a runway with a plane taking off (but lasts about 8 seconds). Kids not fussed at all but my ears were ringing! However the best illustration can be made by my son wearing these defenders and falling asleep sitting on my lap whilst a monster truck was ramaging around crushing caravans, old ford cortinas, buses and making donuts. The best bit is that they are designed to cut out particular frequencies, so trucks, cars and music are all muted, but voices aren't so affected. I could talk quietly, close to my kids ears when there was loud engine noises and they could still hear me. They wore the defenders consistently for at least an hour at one point, without complaining or fiddling. Truely remarkable product. Highly recommended (and about £5 cheaper per set than buying them direct from manufacturer).