Available in super compact 4 and 8-inch versions, the Rollbe measuring instrument is a coin-sized tool designed to measure straight lines and curved surfaces. Whether it’s a sectional sofa, a door frame, a piece of wall art, or the inseam of a pant, the Rollbe is a modern-day measuring tape without needing the support of a companion app. The highly versatile device is both metric and imperial compatible and can easily fit into your pocket.
Rollbe’s Intelligent Design Features

User-Friendly Measurements

“When it passes the number 4 – add the extra inches or fractions of an inch to your measurement. One full circle is equal to 4 inches. Two circles equal 8 inches. Three circles are the same as a foot. Keep rolling and measure.”
Outside of remembering to count rotations and adding the extra inches to your measurement total, the Rollbe does require one additional step when measuring inside corners. Because the Rollbe is round, you have to add the radius or diameter of the ruler to your measurements. Thankfully, the ruler has the radius conveniently located on its ruler face.
Practical Use

Professional Use
The larger 8-inch and 20-centimeter versions are for the designer, carpenter, architect, and fashion designer that need accurate on-the-job measurements before drafting layouts, blueprints, and templates. There is really no job too difficult for the Rollbe since it’s wheel can run across any surface type. It’s really just up to the professional to count the rotations and make some simple adjustments if there is an inside corner to measure.
Bottom Line
There are plenty of fancy digital measuring devices that come with sophisticated apps, but the Rollbe is not one of them. With the Rollbe, you don’t need to worry about opening up a companion app with your smartphone or taking object images before using the device. This is simply an autonomous compact sized, highly versatile, super affordable tool that fits inside your pocket and takes accurate measurements of any object/surface. It does require a bit of human accuracy by counting rotation and adding on additional inches, but with a few Rollbe uses, owners will be capable of capturing accurate measurements without much effort.
Source: Kickstarter
it very nice to use it roller measure on any line curves and edge. where I can buy those 4 items?