Me & Kali
This is the tube fastened on when 'things' are at their smallest......which is the only  way to get it on!
This is after a bit of teasing. No raging erection due to the pain from the spikes....but a definite semi-arousal condition.....which is significant enough to make things hurt! Under usual play conditions, this is about as far as I go. Any more and the pain results in a quick loss of tumescence.
Here you can see the indentations from the spikes. No broken skin, no damage, just little reminder dimples that go away pretty quickly. The only time I looked worse afterwards was many years ago when I first experimented with the tube and forced myself to have a full erection and orgasm in it. THAT s something I don't think my body will allow me to repeat.