servo E-stop circuit

Hello,
I need an E-stop circuit for my Gecko servo system. I've been
looking at Mariss' "servo E-stop circuit" in the files/circuits/misc
circuits section. I need help figuring out what parts to buy.

There are 2 NC (normally closed) 15A 'contacts' in the upper section
of the drawing that switch the braking resistor in during E-stop.
Are these more like relays, or contactors, circuit breakers or what?
I've done some looking at places like automationdirect.com, and they
seem to have them as 'inductive' motor starters (some are for
resistive loads).

What 'device' do I need here (please be specific)? Any
recomendations on where to get them?

If anybody thinks they have a better 'E-stop circuit' that a non-
electrical engineer can build, I'm all ears. Thanks.