Retro Cannondale MTB Frame Aluminium Made in USA 20” for 26 inch wheels. Canti brake as no disc mounts. Sound frame, a little surface corrosion but nothing serious. Looks to be running a 1-1/4” head tube so a reducer kit will be needed to fit standard ahead 1-1/8” forks. Smooth square taper bottom bracket. Not sure which model but has the cups from a Shimano XT headset still fitted.