Well, this is a guess, but I reckon we can work it out by a process of elimination; 'Come here Watson!'

Firstly I'm pretty sure it's not bakelite! LOL! (Now I'm gonna look really stoopid if it is, aren't I?)
Secondly, it's a cheap and nasty kit (or should I say RTR), and even in better kits, the aluminium shoes are an upgrade.
Therefore, it has to be Teflon.

Could be wrong, but that's my logic...elementary...