allowable error system with double units

beam with double reinforcement

boilers with double rows of tubes

cable-stayed with double pylons

case history folder with double side

closure with double dykes

cold-rolled deformed bar with double wing

conductor with double insulation

diamond drilling technique of single power with double pipe

disk flying shears with double length size

double beams

Double Exposure

double two high rolling mill

extrusion head with double tubes

grinding mill with double rotating directions

heat exchanger with double moon

Heat pump with double high-temperature heat source

insertion of needle with double hands

involute gear with double pressure angles

KK-joint with double chords