34mm ID 44mm internal length (44 mm is the lenght of this tube specifically). Combined with the base ring, this fits comfortable length up to 90mm with a snug fit, no room for growth. lower end closer to 60mm and you would have a little room. Fairly open, comfortable cage that is easy enough to clean and comfortable for long term wear. Touching isn't restricted so teasing with your partner is possible! Compatible with Base Ring 12 50.8 V1 and a small brass lock.