It is the threaded version meaning you have to thread it in to install it. The Silver Sentinel Filter utilises a thick filter medial to capture the particles inside the filter not just on the outside. This filter will filter down to 1 micron where other cartridge filters go down to only 70 microns. This filter is completely maintenance free. Just install it and forget about it. **Every three months just replace it.
* If not sure whether this fits your spa consult your manual or your dealer.
** Based on average use, may require replacing more or less frequently.