An apparatus for gripping a substrate on its peripheral edge including a substrate support having proximate and distal ends, at least one distal rest pad disposed at the distal end, the at least one distal rest pad includes a back stop portion and is configured to support the peripheral edge of the substrate, at least one proximate rest pad disposed at the proximate end, the at least one proximate rest pad being configured to support the peripheral edge of the substrate, and an active contact member assembly disposed at the proximate end, the active contact member assembly including a pusher member, a contact member and a rotatable coupling member that are reciprocably movable towards the distal end for urging the substrate against the back stop portion, the contact member being rotatably secured to the pusher member and free to rotate about an axis of the rotatable coupling member.