However, it was enough to recall the product as a precautionary measure, Kmart said.
No injuries had been reported, it said.
A total of 10,993 of the kid's helmets were sold in New Zealand between October 2012 and April 2014. They were designed for use with skate-boards, bicycles and scooters, and came in a range of colours and patterns.
Anyone who bought one of the affected helmets is asked to return it to their nearest store for a full refund. No receipt is necessary.
Kmart has stores in Auckland, Hamilton, Tauranga, Palmerston North, Hastings, Nelson, Wellington, Christchurch and Dunedin.
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RECALLED HELMETS:
* Model number, which can be found on a sticker on the inside of the helmet: FM-170/2500
* Descriptions include:
Skate helmet black S/M, XS/S
Skate helmet pink S/M, XS/S
Skate helmet splat S/M, XS/S
Skate helmet camo S/M, XS/S
Roller Derby skate helmet S/M
* Customers can contact Kmart on 0800 945 995 for further queries.