Amazon.com An essential tool for serious building professionals(view larger). Ideal for contractors, builders, architects, engineers, and other serious building professionals, the Construction Master 5 Construction Calculator (model 4050) from Calculated Industries helps you get fast, accurate constructionmath calculations in the office or on the job site. Reduce the risk of expensive errors when estimating costs and materials. Enter the numbersjust as you would say themand the solutions appear in an instant.The Construction Master 5 works in and converts between building dimensional formats: yards, feetinchfractions, decimal feetinches and metricincluding area and volume. A custom rafter function provides common rafters, regular and irregular hips, valleys and jacks, while a rakewall function determines stud length for any oncenter spacing, in ascending or descending order. Other dedicated functions include stair calculations for risers, treads, stringer length, and incline angle; solutions for circles, arcs, columns, pillars, windows, postholes, and more; and board feet lumber estimations.Other features include solving for cost per unit, a paperless tape that lets you review the previous 20 entries to doublecheck your totals, ability to store preferred fractional values and dimensions, and work with standard calculations.Its powered by a single CR2016 battery (included), and the Construction Master 5 has an auto shutoff feature that turns the calculator off after about 8 to 12 minutes of nonuse. The calculator measures 2.95 x 5.7 x 0.67 inches, weighs 4.5 ounces, and comes with a hard protective cover with a pocket reference guide. Its backed by a oneyear limited warranty.Whats in the BoxCalculated Industries 4050 Construction Master 5 construction calculator; protective slide cover; quick reference guide; pocket reference guide; battery4050 Construction Master 5 Construction CalculatorAt a Glance:Essential tool for building professionalsWork in and convert between dimensions, area, and volumeincluding metricComplete rafter, roof, and framing solutionsBuiltin rightangle calculations with automatic squareupsPowered by single CR2016 batteryOneyear limited warranty From the Manufacturer The Construction Master 5 is fun to use. Quickly find solutions to building and dimensional problems that seem to comeup and you havent used the math formulas for years. Enter the numbers, just as you would say them, and the solutions appear in an instant theyre builtin to your Construction Master 5. Reduce the risk of expensive errors when estimating dimensions, costs and materials. Save time, money and frustration!