The Hydro-Photon SP-RC is the correct replacement cartridge for the following:
The SteriPEN SP-RC Pre-Filter Replacement Screen is a replacement cartridge for the Water Bottle Pre-Filter and the FitsAll Filter from SteriPEN. This SteriPEN prefilter screen reduces particulates through the use of a 40X40 micron size nylon mesh filter. The replacement screen maintains the quality of your pre-filter and maximizes UV purification efficiency.
SteriPEN SP-RC Pre-Filter Replacement Screen specifications: