DIY filter sock for reef aquariums

Personally I don’t use them, haven’t for many years.
Back then I called mine pre filter bags.
I use sliding barriers and or settling pre filters, they are much more efficient and very easy to take out and clean and replace.
I made a sock set up all in one incorporating pre and settling to show the guys, as much as you can with a bag/sock style and the pic that follows is the inner sock only, as its called these days, by these days I mean over the last 20 years or so.
It will be in the DIY section soon
Making your own sock takes a slice of pvc pipe,fishing line,holes via soldering iron, wool blend wadding that you cut to size and a little silicon to glue it all together costing maybe $1 each in materials.
You can’t see it easily, but there is a fishing line handle hanging in the sock as well.
This is the result.