T-Tario footmuff?

[mrspeachykeen]

I have the Teutonia T-Tario 32 carseat. It comes standard with a footmuff. We are going to be traveling to Michigan this week where the temps are down in the teens. I tried the footmuff out today and it seems like it was designed to use with the head support which we've long since needed. The footmuff only really covers up her legs. Is that where it should be covering? I've looked at the manual and am pretty sure that I've installed it correctly, but it doesn't say what size baby it is really for.

Does anyone have any experience with these footmuffs?