Well, I'm surprised to say this, but (1) I have been using the Mapleshade tube dampers for over 6 months now, (2) I still haven't broken any of my tubes and (3) on balance I actually like the effect they have, though I find the effect to be similar to Andy Bouwman's (Vintage Tube Services) octal tube dampers, more so than Mapleshade might believe. I think that they do tend towards making the sound a little on the bright side (compared to undamped tubes), though I have found this to be the case with all tube dampers I have used; that is my main reservation about them outside of their logistics. I think that being made of brass they should in theory ring more than a lead or O-ring damper, but the sheer mass of these things offsets that, and I don't really like an over-damped sound that much anyway. I will point out that these things do get really hot to the touch, bear that in mind if you try them.