The high E facilitator is sold by J.L. Smith in both aluminum and delrin plastic. They are sold by the size of the tonehole. The only negative I have heard about the "donuts" is that they help but are not as good as the split G key in producing an easy to play high E.
http://www.jlsmithco.com/E-FAC/HIGH-E-FACILITATOR-ALUM-510
John