ZoneBloc®, Type Z, is a proprietary temporary concrete barrier developed by Hill and Smith. It has been successfully crash-tested in accordance with MASH Test Level 3. ZoneBloc® has been designed as a narrow barrier being only 300 mm (12 in) wide. ZoneBloc® is approved as a freestanding, narrow category III barrier. There has also been a variant called ZoneBloc+®. This is a restrainable version to meet restraints permitted category IV standards.