Stethescope for peds..

Today I worked in the pre-admission testing for the outpatient peds OR today and somehow let a child slip by that had crackles in one lung. Not that it is someone else's position to catch my mistake, but the RN didn't hear it either. CRNA about to do the case supposedly heard it and case canceled. I honestly never heard it. Parents upset and MDA even more so. I know what lung sounds are heard as, I don't think my brain or ears are the problem. He was a little underdeveloped preemie when he was born and didn't appear to grow much since then.
My question to you guys is "What stethescope do you use for your PEDS patients?" My littmann master cardiology has a fairly large head on it, I know they make an adapter that goes to a smaller size supposedly for bones and joints, but I think this is what reached up and bit me today as he was really tiny. I kind of need to avoid this repeat episode that happened today, I was wondering if any of you bought specialty peds stethescopes, esp for the really little ones.

Thanks guys,

now 1/2 posterior rn29306