16'' bike for 4yr old

I've been looking at the ridgeback mx16 or the specialized hotrock 16 but the spesh doesnt have a rear v brake that is important for skids.any other sugestions would be good .and just in case you think 16'' is too big for him he's giant 4 yr old and he likes blue bikes.
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We`ve been very pleased with it.Nicely made little bike.
2010 Giant Defy Advanced
2016 Boardman Pro 29er
2016 Pinnacle Lithium 4
2017 Canondale Supersix Evo
Measure him, then take a look on islabikes sizing guide, stuff like inside leg is most important.