Toggler snapskru, 20 pack, 3/8"-5/8", sp self drilling drywall anchors with #8 x 1-1/2" screws, when activated with a screw anchor opens with an audible pop locking the anchor on the wall, drywall gypsum & its paper are kept in compression & thereby immediately reinforced, built-in positive stop that prevents overdriving the anchor when using a screw gun, vibration & shock resistant.