Sparco Pro Shell rib protector for karting and go-karting is a good and affordable rib protector for those who do not need to use protectors with chest plate and FIA approval. 
Inside in a fabric with 3D mesh with good air permeability and protective parts of a soft plastic material in honeycomb pattern. 
Great customization possibilities allow you to convert the cover to several different sizes and use it for a long time.
The Sparco Pro Shell go-kart rib guard is a good choice for both adults and children regardless of the racing class.