Abstract: Devices, tools apparatus, kits, systems and methods for providing a gauge and tool for allowing a single installer to install siding boards, such as cedar and pine lap siding and Cementous boards on exterior walls. An installer can use two gauges to and install exterior wall siding on all sides of a building without a second installer. Each gauge can be cut from sheets of metal, such as aluminum having a thickness of approximately 0.09 inches. Each gauge can have a front generally rectangular panel with a left bent side with an upper left ledge and a lower left step, and a right bent side with an upper right ledge, and a lower right step, a first top middle panel extending upward from the rectangular panel between the left bent side and the right bent side, and a first mounting hole through the front generally rectangular panel. An installer can initially mount a bottom first siding panel on a wall. The gauges can allow siding such as 7.