PanSaver 45950 Foil Electric Roaster Liner Pack of 4 - Fits 16-22 Qt Roasters - up to 400 Degrees

Item title says pack of 4, but box pictured says 2 and description says 2 per box. Are there two boxes in this listing on Amazon?

It says that it's safe to 400 degrees, but the melting point of aluminium is over 1,000 degrees. Are these coated with plastic or something? Why 400?

Which liner should I use to cook dressing for Thanksgiving?

do you get 4 packages of 2 which is 8 liners?