The Jumbo Penis Cake Pan holds a full box of cake mix.
The Mid-sized Penis Cake Pan holds 3/4 box of cake mix.
The Small Penis Cake Pan holds 1/2 box of cake mix.
Durability
The second question you must ask when buying a penis cake pan is, do you want to be able to reuse it or would you like to throw it away? Disposable penis cake pans are cheaper, but if you plan on making any penis cakes in the future it's worth the extra money to invest in a durable penis cake pan.
Disposable Cake Pans save on the mess.
Durable Cake Pans are a good investment.
While you're at it, here are some more great bachelorette party planning resources:
How to Be a Maid of Honor
Bachelorette Tiaras
Bachelorette Party Playlist
Gummy Penis
Black Bachelorette Party Supplies