From Prevail’s page for them,
“These switches have a full nylon housing*, POM linear stem and 58.5g stainless steel spring.”
" **Nylon housing is a different type of nylon compared to their other offerings, to keep the price down. Sound & performance may differ from other full nylon housings.*"
Sounds like JWK is using the cheapest nylon they can get for these TBH. Would makes sense with them not willing to put their proper name on it. Kinda a shame, but I’ll stick with Gat Pro yellows for my budget switch for now.