Hillman Keyhole Hanger in the Picture Hangers department at Lowes.com
Cutting Keyhole Slots for Hanging Pictures and Plaques - YouTube
Geesatis 50 pcs Keyhole Hangers Heavy Duty Single Hole Hanging Plates Metal Picture Hanger, with Mounting Screws, 43 x 16 mm, Silver, Flat Surface - - Amazon.com
Hillman Heavy Duty Keyhole Hanger Double Hole in the Picture Hangers department at Lowes.com
Keyhole Hangers (Mini) Picture Hanging Kit holds up to 100LBS In stud.