Molly, it's really no biggie. If he suggests it, I'd go for it. It made a world of difference for us (for a while). And the odds of him needing a 2nd set are slim (5% for kids under 1). Since he's over 1 he may not ever need another set. They are only under anest. for 10 minutes tops. And the recovery is practically non-existant.

H, I don't know if they are tall or not!! They are skinny. But I don't have many kids around their age to compare height to. I think they are probably around 34"??? Is that tall for 21 months?