A Christchurch dairy owner's already implemented their own fortress-like protection - and it's working.

This comes as a Hamilton dairy owner's installed a metal cage to vet those entering his store, after being attacked by armed robbers.

Linwood dairy owner Violet Lwee says they collect customers' purchases from behind a caged area only staff can access and don't pass it through the grill until the shopper's paid.

She says it's safer for everyone, and means there are no worries for staff moving around the shop.