Super cozy fleece booties with organic cotton liners and anti-slip grippers. Sizing: US 1 (0-3 Months, 3.5" Sole). US 2.5 (3-6 Months, 4.0" Sole). US 4 (6-12 Months, 4.5" Sole). US 5.5 (12-18 Months, 5.0" Sole). US 7 (18-24 Months, 5.5" Sole).