This latest batch is maybe 1/8" wider and taller than the prior batch-- enough it's hard to fit in the plenum. I think I was able to get it in there well enough to seal. But it will make me think before buying more.
I have replaced Aprilaire filters in the past and it was one giant pain! This installation was very easy once I figured out just how to fit it in the frame. I will be buying another one in the future.