The Japanese metric measuring wheels are available on Amazon.

http://www.amazon.com/gp/product/B002KL0OTE

Measuring wheels are handy for measuring curved lines on patterns. Comparing an armhole length to a sleeve head will give you the amount of ease built into the sleeve. I find them especially handy if you have done fit changes and need to see how those changes affected your pattern.  Find on Amazon:  http://www.amazon.com/gp/product/B002KL0OTE

Happy Sewing!

Claire