Baskerville Ultra muzzle sizing help

So, I am attempting to order Chloe a Baskerville Ultra muzzle...however, I am so not sure what size I need since two different sources are telling me two different things.

I measured her snout length and her muzzle circumference with a piece of string, then laid that out next to a measuring tape. I measured her snout length as 3.5" and her muzzle circumference as 9.25". (She's a 45 pound Collie/Aussie mix.)

I was looking around at a few different sites for sizing information...Leerburg says for her measurements, I need a size 4 muzzle (Size 4: 3.25", 12.25"), but another site (some online pet retail store) says a size 2 muzzle would fit her (Size 2: 4", 11.8").

So now I am royally confused. I know quite a few members on here have one of these muzzles so...which size should I go with?

3.5"? Really? That sounds tiny...

My Dutchie wore a size 4, she sounds like she'd be about his face-size.

She's got a little nose. LOL I can put the base of my hand at the tip of her nose and reach clear up to the bottom of her ears.

ETA: I'm thinking a size 3 would be too small, but I'm worried a size 4 will be too big. Her collar size is 12-14", I think...I'm worried the muzzle will be to loose.

I decided to go with my gut for Eve, whose "recommended" size was 3, but I got her a 2 and it fits perfectly. a 3 would've been huge.

I think they run a little bit large, or our girl dogs run a little bit small. Sometimes bitches need a smaller size to account for their slimmer heads.

Yah, I think I'm going to go with a three. Is there a better place to order from in case I have to return it?

Quinn and Chloe are probably around the same size and Quinn is a size 3. It's a little narrow on her nose but she was swimming in the 4.