Kreg 1-in Corner Clamp in the Clamps department at Lowes.com
Bora - 90 Degree Quick Release Corner Clamp
JPB Corner Clamps For Woodworking, 90 Degree Clamp, 4PCS Adjustable Spring Loaded Right Angle Clamp Set for carpenter, drilling, wood cabinets, frame | Pro Carson clamps for woodworking (5-22mm) - Amazon.com
90 Degree Clamps for Woodworking Positioning Squares Right - Etsy
Wood Corner Clamp Right Angle 90 Degree with Adjustable Jaw – FindBuyTool