Continuous spiral staircases for interiors and exteriors ready to be used for 3d models or 3d printing. Treads and risers are in standard sizes. Riser is 6 inches. Width of stairs in 3'-8and handrail level is 2'-6. Available in lower versions of sketchup 2003 to 2020 versions included. Only 1 materials used in 3d file. Also available for 3d printing. Formats OBJ, 3DS, STL available. Files included are JPG, vector pdf, sketchup files in higher and lower versions.