my guess is they are talking about this part:
http://octopart.com/6127v1a360l.5fs-...ogies-19910150
There are a number of different options it can be ordered in, see
data sheet
Note these are rated at 500 RPM in the datasheet. So they likely more than sufficient for monitoring the position of a part - like the wheel's heading in this case. Without proper gearing they are likely not a good choice for use on things like a shooter wheel. If you're looking to monitor wheel rate of travel over ground, these aren't appropriate unless you've got wheels bigger than 6" or have geared the encoder down (assuming you're targeting a top speed or around 14fps).