I use the Penimaster Pro, for about 6 hrs a day, done in 3, 2hr sessions. No blisters, ever. After a bumpy learning curve, it is easy to put on, pain and discomfort free. I retired my X4 after ~ 3 yrs of use. It is all about being able to get in the hours with zero pain, discomfort, negative side effects. The Penimaster Pro can accomplish this.