Hello
I've been practicing ballbusting for some time and in my last vacation I bought this toy, it is called The Ball Buster:
http://www.misterb.com/en/play/cock-...he-ball-buster
When trying it with my girlfriend I had the greatest time, I came almost without stimulating the penis.
The pain was not overwhelming, I felt like she could turn each screw some 2 more times before I started begging her to let me go, but we did not carry it on further because my girlfriend was worried about my balls turning purple from the pressure.
I tried looking over the internet but could not find safety information about how to use this kind of toy without risking damaging the balls. Clearly it cannot be turned until the end because the screws can be turned until there is literally no space between the plates, but is the mild pain a good indicator that it is safe to continue turning? Are there other kinds of signs I should be looking for? Do any of you have experience with this kind of toy?

Thank you