Locking wheel nuts

Hi All,

Fitted the 17" tt alloys purchased from Jeremy yesterday, they look great, many thanks. Noticed when fitting that at some stage in its life, the locking nuts had been removed and replaced with the plain type.
Being on the cautious side and wishing for my son to remain on 4 wheels, has anyone any recommendation on locking wheel nuts. Began to look but on some eBay ads there's a note saying about the chamfer and need to check against wheel type.

Any pointers greatly appreciated as i'd like to get these on order. Happy to purchase from anyone who's after selling a set if any spares going around.
Many thanks