On the web they only accept Paypal.
Go to kings.
Go to the motorized bike sprockets section.
Example here:
http://kingssalesandservice.com/motorized-bike-sprockets/
On the right side of the screen you have your choice of size range.
Pick one.
On the next screen you can pick a color and the size you want.
On the right side of the screen, under the Sub-total tag, there is an option to go to check out.
Click on it.
Fill out the information boxes.
After that, before you pay, you will be given the option to leave "notes to seller".
In this "notes to seller" box, tell them what sort of mounting you want.
I.E. Ragjoint, 6 hole bicycle disc brake or even a custom pattern if you know the dimensions necessary.
NOTE: The sprockets already come drilled with the most common mounting patterns including the ones mentioned above.
(I asked for the SBP shift kit pattern and did not have any extra holes in mine.)
Pay and wait.
I never received any shipping information from them.
I never received email or any sort of correspondence from them.
I only received confirmation of payment from Paypal in my email.
The sprocket arrived via USPS in about 14 days.
The sprocket is awesome!
Note: you can always call their phone number listed on their site.