You can imagine a balloon that gets filled up with water, and then you have this tense sheath that's surrounding the balloon, and that's what gives you the stiffness with an erection. And the fracture is a rupture of the balloon and the sheath surrounding the balloon, the vast majority of cases are one-sided, or unilateral, corporal ruptures. But sometimes Rajveer Purohit do have someone who's had a bilateral, or two-sided, corporal fracture involving the urethra.