It's so disappointing when a mitten disappears (socks too :) !); mitten clips help keep mittens there when you need them! Simply clasp one end onto any fabric (think coat sleeve) and the other end onto the mitten. Durable clasps make it hard for toddlers to unclip (parenting win!).
Use mitten clips for other things too! Clip a blanket on tight, keep a toy off the ground, even use them for your adult self, keeping your mitten close by rather than shoving them in your pockets!
Sizing
One-size.