Bathmate Hydromax8 Penis Pump - BlueNewest to the range, the Hydromax8 is designed for a user whose penis is 6 8" (17. 5 23cm) when erect. After a large volume of feedback from 7 users, we discovered many people were looking to size up but the 9 was just a little bit too much of a jump up in size. The majority of customers sit in and around the 7 mark, so it made sense to bring in an additional size pump to fulfil the requirements of users who wanted a larger pump but werent quite ready