This is a small adults so is quite large but okay for the bigger kids (see pics of test version).
There’s no kids version available atm, sorry. 
• 100% polyamide
• Fabric weight: 7.13 oz./yd.² (202 g/m²)
• Regular fit
• Hood with a drawstring, zipped closure, elastic cuffs and hem
• 2 zipped pockets
• This product’s fabric is OEKO-TEX Standard 100 certified and PETA-Approved Vegan