Adaptor for 715-2 Cartridge Type Electronic Gaging Head. The 673 Series Bench Micrometer can also be used with the 717 Analog Amplifier or the 776 Electronic Gage Amplifier by using this 673A Adaptor for the 715-2 Cartridge- Type Electronic Gaging Head to read to ten-millionths of an inch (.000010") or 0.0001mm.