AS1428.2-1992 Design for access and mobility - Part 2, clause 9(c) states:
If gratings are located in a walking surface, they shall have spaces not more than 13mm wide and not more than 150mm long. If grates have elongated openings, they shall be placed so that the long dimension is transverse to the dominant direction of travel.
ACO offers a range of Heelsafe® grates that have openings of less or equal to 7mm.
A range of rated Heelsafe® Anti-Slip grates are available from ACO and are certified to AS/NZS 4586: Slip Resistance Classification.