You can wear these briefs comfortably all day with your Packer or STP safely inside it's packer pouch.
In addition to holding your junk in place, you can use these as a harness for your sexual prosthetic to avoid or eliminate the straps of a strap-on style harness and create a more realistic sexual experience.
XS / S = 28-32
M / L = 32-36
L / XL = 38-42