Please look at the size chart carefully, thanks!!!
The kid's LED shose' size chart

8 M US Toddler----US Size 8 M----foot length 5.51-5.90 inches

9 M US Toddler----US Size 9 M----foot length 5.90-6.22 inches

10 M US Toddler---US Size 10 M----foot length 6.22-6.50 inches

11 M US Litter Kid----US Size 11 M-----foot length 6.50-6.69 inches

12 M US Litter Kid----US Size 12 M-----foot length 6.69-7.08 inches

12.5 M US Litter Kid-----US Size 12.5 M---foot length 7.08-7.28 inches

13 M US Litter Kid------US Size 13 M---foot length 7.28-7.48 inches

1M US Litter Kid-------US Size 1 M-----foot length 7.48-7.68 inches

1.5 M US Litter Kid-------US Size 1.5 M------foot length 7.68-8.07 inches

2.5 M US Litter Kid-------US Size 2.5 M------foot length 8.07-8.46 inches

3 M US Litter Kid-----US Size 3 M------foot length 8.46-8.66 inches

4 M US Big Kid------US Size 4 M------foot length 8.66-8.86 inches

5 M US Big Kid------US Size 5 M------foot length 8.86-9.25 inches

Product include:
1*Boy&Girl LED SHOES with charging cable

• Note: Please measure your feet length and refer to our Size Chart. For example, It's normally US size, and you can measure your son's feet length and if he fit the size of "US Size 2 M-----foot length 7.48-7.68 inches",and refer to the PRODUCT DESCRIPTION, then you can choose the 2 M.
• SWITCH INSTRUCTION: Hidden switch button, 1" beside the usb outlet, along the inside hem. Push around and you'll find the "click." Press it to switch on.It starts with steady red light.With each press,it changes to another light mode.Press the switch for 9 times to turn the light off.
• CHARGE INSTRUCTION: Easy charge like your cell phone with the attached USB charging cable.Switch on the shoes when received and light up until all power gone.Then charge both shoes for 3 hours.
• LIGHT MODES:1.light on from red(steady)-2.green(st')-3.blue(st')-4.yellow(st')-5.skyblue(st')-6.purple(st')-7.white(st')-8.auto-change mode-9.light off
• If you receive the LED shoes can not work, please do not worry, it may have not electricity or the charger is bad, you just give it to charge, it will light up.

Note: Please measure your feet length and refer to our Size Chart. For example, It's normally US size, and you can measure your son's feet length and if he fit the size of "US Size 2 M-----foot length 7.48-7.68 inches",and refer to the PRODUCT DESCRIPTION, then you can choose the 2 M.