Came that way- that is their high speed low drag NP3 coating.
"NP3? is a combination of a nickel alloy plating combined with
Polytetrafluoethylene aka Teflon. The plating components with
electroless or autocatalytic nickel is one of the most rapidly
developing metal finishing processes. The advantages of coating
uniformity, corrosion resistance and hardness are providing designers
with opportunities to protect and improve base materials in ways that
were not previously possible."
http://www.pof-usa.com/p308/p30814.htm