Their Nickels were formerly called "Slappers", now known as Nickel Series. If these are the ones you mean, they have a strong upper-mid "snap" and more "Guts" than any of the more common Nickels. Better sustain too, for a Nickel RW. They are slightly higher in tension, which I feel contributes to their unique tone and playability. Best sounding Nickel for me.
Ian "Conjureman" Aniano