42mm Female to 28mm Male Bottle Adapter

The is a two piece adapter that allows you to attach a bag or container with a 42mm male thread like a Befree or Hydro_pack to a water filter with a 28mm female thread like is used with the Sawyer Squeeze water filter.

Both parts can be made from PETG, but if the center piece is made using TPU it will seal better.  For the center piece it should be made using food safe grades of PETG or TPU.