Nord-Lock washers are available with an enlarged outer diameter, referred to as SP washers.
SP washers are designed for use on large / slotted holes, painted / sensitive surfaces or soft materials. Use Nord-Lock SP washers with flanged bolts or nuts for optimum load distribution.
By using SP washers, the load is distributed over a larger surface which can be more gentle for sensitive surfaces. Please consult Nord-Lock to find the optimal solution for your application.