This device has proven so useful.  When I think my kids may need a new shoe, I just measure them at home and off we go.

When you get it, make sure to read the instructions.  I use the arch measurements as well as the foot measurements to get the correct size.  Even at the shoe store, the employees often neglect the arch measurements.  Some stores have these devices without any arch measurement markings whatsoever (a la Payless Shoe stores).  Basically, the arch measure measurement (that part that you slide to the joint of your big toe) gives a shoe size and the foot measurement (the measurement to your longest toe) gives another shoe size.  Compare the arch and foot measurements and buy the larger size.  The instructions are also on the Brannock company website.

This device also measures the width of the foot.  Both of my kids tend towards wide feet, but they seem to grow in and out of it.

The Ultra Fit Jr. model differs from the other models, because it is made of plastic and only measures children`s sizes.  That's fine with me.  Metal is so darn heavy.