Three bolt equipment

Three bolt equipment, (Tryokhboltovoye snaryazheniye, Russian:Трехболтовое снаряжение, Russian:трехболтовка) is a type of standard diving dress which was used by the Russian Navy in the 19th and 20th centuries. This standard diving dress consists of an air-supplied copper helmet that is fastened to a waterproof suit by three bolts, together with the diving suit itself, two 16 kg lead weights attached to the chest and back, and heavy boots made of copper and lead.