After 20 years or so, my SLIK helmet liner finally gave up the ghost, and I found out that they are (apparently) not made any more -- may be a few still around gathering dust on a dealer's rack, but now out of production.
I've tried a few others, and - for one reason or another, have found the design to be sorely lacking -- elastic edges that are too tight, material not "slick" so the helmet is hard to pull on, seams in the wrong place(s), etc.
Enter the SILKY from WHITEHORSE PRESS! $18.95 ea. or 2 for $34, in all colors as long as it's black. Yes, you'll look like a Russian Cosmonaut until you get your brain-bucket on, so NO NEED to give up that flash of the "maximum Dork" look, ever again! (No affiliation w/ Whitehorse beyond loyal customer.)