Cell division factor that enhances FtsZ-ring assembly. Directly interacts with FtsZ and promotes bundling of FtsZ protofilaments, with a reduction in FtsZ GTPase activity. Mostly homodimer in solution. Interacts with the C-terminal tail of FtsZ. Localizes to mid-cell in an FtsZ-dependent manner. Localization does not require FtsA, ZipA, ZapA or ZapC. Mutants are viable, with no discernible division phenotypes. Belongs to the ZapD family.