The liners is very durable. I have had my VK2 a long time and use it all the time. I have never worn out a liner. Every once and a while I replace it. Once you get the liner adjusted for maximum pleasure you really don’t like to mess with it.
Akbees, I do notice some stretching out of the liner over time but never to the point that it looses the squeeze. Probably has something to do with size and firmness of your cock. I use a 2.50 housing and either a 2.25 or 2.38 liner ( I have a couple plus 1 with a stroke sleeve)). I just use ID or Wet. OR you use your VK2 a lot more often than I do….(I average 2 or 3 times a week)…but really long sessions.