Kids bindings

Purchasing a hyperlite 109 for my 3 year old son who weighs about 32lbs. I am buying it from
wakeaction.com and 1 binding Size choice is k12-m5 and that other two are 4-8.5 mini and 7-11std. He is. Size 9 shoe. What bindings do I get. The hyperlite motive jr comes with k12-m5 bindings and the hyperlite motive comes with either mini or std. Which one do I buy?

Sounds like the k12-m5 is the smallest one and he still has room to grow into them.

I agree with Kane. I believe that is what my daughter has.