Convenient and Accessible. Ideal for planning and estimating – handy pop-up with CAD or spreadsheet programs, Work in and Convert Between All Building Dimensional Formats, Feet, Inches, Fractions and Metric - Including Square and Cubic Formats. Custom Rafter Keys: Find Common, Regular (45°) and Irregular (non-45°) Hips/Valley and Jack Rafters, Jack Rafter Functions: Provide complete solutions in ascending or descending order for Regular- and Irregular- pitch roofs. Instant Rafter Cutting Angles: Cheek, Level and Plumb Circular Solutions: Arches, Column/Cone, Pillars, Windows, Post-holes and more Rake-Wall Key: Determine each stud length for any On-center spacing; ascending or descending order Stair Solutions: Risers, Treads, Stringer Length, Incline Angle Trigonometric functions: simplify complex construction-math; Sine, Cosine, Tangent, Arcsine Arccosine and Arctangent D:M:S to Decimal Degree Conversions Automatic Block and Footing Solutions Backspace Key Ten built-in Memories: Store constants and accumulate values Preference Function For User-Defined Options: Custom-Set Fractions: 1/2, 1/4, 1/8, 1/16, 1/32, and 1/64 Constant Operator Exponential Notation Requires: Operating System: Pentium 166MHz or greater Windows 9x, ME, 2000, XP 6MB or greater memory 16MB Free Hard Disk Space CD-ROM Drive Not Available for MAC