Hydro-photon Pre-Filter Replacement Cartridge

I own the SteriPen and wanted something to serve as a prefilter other than a coffee filter, so I purchased one of these prefilters. Although the thought is good, I pretty much thought these were junk and felt so inclined to even send my thoughts to the manufacturer. It is essentially an open mesh which requires the user to constantly screw and unscrew the cap. the biggest problem is water will spill out whether the nozzle is right side up or down and the seals around the bottle itself drip. No matter what I did, I got nothing but leaks on two of them. I returned them and actually decided entirely to get away from the SteriPen because I was so disgusted. I ended up going with tablets or liquid treatment and had a secondary Frontier filter which was much smaller and lighter anyway.