Concrete bases for air-termination rods, for protecting small roof-mounted structures on flat roofs and for installing spacers, e.g. for isolated ring conductors or for self-supporting air-termination rods with tripod (only with a weight of 17 kg). Stackable, for air-termination rods Rd 16 mm, chamered, tapered, or DEHNiso spacers Rd 16 mm.