Right Angle Clamp, MAIERZI Single Handle 90° Aluminum Alloy Corner Clamp, Right Angle Clip Clamp Tool Woodworking Photo Frame Vise Holder with Adjustable Swing Jaw - Silver Gray - Walmart.com
United Mitre Vise
Bora 90 Degree Corner Clamp Bora 551025 – the Quick Release Corner Vise That Holds Your Material Fast at a Perfect Right Angle, Making Frame and Box Projects a Breeze. - Angle Clamps - Amazon.com