A module is an interchangeable part on a compound bow that lets you adjust draw length, often letoff, and sometimes peak weight without swapping limbs. Every cam manufacturer has its own module system, but the function is the same across the board: it’s the small piece that makes your bow fit you.
Where Modules Sit on the Cam
Modules usually live on the cable side of the cam. You’ve got a string side and a cable side, and depending on the cam system, you might have modules on both.
They’re small aluminum parts. On cheaper bows, you’ll sometimes find plastic ones, which I’d avoid unless you’re putting a brand-new archer on a starter bow. Quality aluminum holds up.
Each company prints a module chart with labeled sizes. The mods are adjusted with screws using a hex or Torx key, typically in quarter-inch, half-inch, or one-inch increments.
What Modules Adjust
The big three: draw length, letoff, and on some systems, peak weight.
For draw length, the mod is what dials your fit on the bow. Newer Hoyt models like the RX-10 offer quarter-inch adjustments, which give you a much finer setting than older designs.
For letoff, look at the farthest end of the module from where the axle sits. That spot is your draw stop. On newer Hoyts, a small mod flips to set the wall as either hard or super hard, depending on how solid you want the back end of your draw to feel.
That same piece moves up or down to set your letoff. The further you set it from the axle vertically, the lower your letoff. On a typical setup, all the way down puts you at 85%, then 80, then 75.
For peak weight, Mathews has built mods into a lot of their newer models that let you change poundage by swapping the mod itself, no limb change required.
Why This Matters Compared to Older Cam Systems
Back in the day, cam companies were chasing efficiency at every specific draw length. That meant a dealer had to stock an actual cam for every draw length position, with no real adjustability built in. If you wanted a different draw length, you were swapping cams.
Modern modules opened that up. You’ve got a much bigger range of adjustment built right into the cam, and a lot of the newer mods don’t even require a bow press to change. That’s the difference between getting fit on the wall in five minutes versus tearing the bow down.
Putting It Together
Mods are the small parts on your cam that let you adjust draw length, letoff, and sometimes peak weight. They’re what make today’s bows adjustable, and they’re the piece that gets your setup fit to you without limb changes or major teardown work.
Get your mods dialed first, then cut your arrows to match.
