Stayput White Attachment Knobs for Shock Cords used with Canvas Covers, 10 Pack Stayput White Attachment Knobs for Shock Cords used with Canvas Covers, 10 Pack 10 Pack of White Shock Cord Attachment Knobs Look for our Pull Cord to stretch the Shock Cord onto the Knob! Quick & Easy to Use! No more tired fingers from Snapping on Covers!