Anal Masturbation Question

[Gaybaby94]

What is the maximum recommended length of an object for anal masturbation? How deep should something go up there? I want to go bigger but I don't want to hurt myself either.

[volleyball17]

im not sure if there is a length but id assume it would be 8 or 9 inches since that is about the size of the largest. 6 or 7 would be more average.