I have them in a few models and will echo others, yes its worth it. I have grown so used to using them that I find it annoying to have to look at the external level now. They did a good job of making it not stand out an be distracting. You have to shift your focus a little to see it and it doesn't distract from your sight picture. I got a ER-25 that didn't have it in a trade, it went in for the update straight away.