The product is composed of a bottom plate, three different kinds of metal wire (copper wire, iron wire,nickel chrome wire), terminal, connecting piece etc..Base:460×150×16mm,technical parameters of metal wire:a copper wire, diameter:φ0.3mm±0.04mm, effective length:400mm±2mm，0.12Ω；a iron wire, diameter:φ0.3mm±0.04mm, effective length:400mm±2mm，0.334Ω;two nickel chrome wire, diameter:φ0.3mm±0.04mm, effective length:400mm±2mm，6.3Ω；