ISIS spline bottom bracket interface. Used Race Face Turbine drive side crank arm. 180mm was popular with the single speed mountain bike crowd, as well as BMX racers. Right arm only, no left arm is included.
Here is a used 90s-era Ritchey Logic triple crankset made by Sugino in Japan. Original black anodized Ritchey chainrings are 26 / 36 / 46 tooth in the 110/74 BCD size. Rarer 180mm crank arm length.