5/8in. AA03 STYLE INVERT-A-BOLT™ FASTENERS. Use these to hold the workpiece in place in some machining operations. These are brand new, never used. $50 price is per piece; mfr price is $90 ea.
From the mfr's promotional material:
The 5/8in. AA03 STYLE INVERT-A-BOLT™ Fasteners are the go-to choice for machinists looking for a robust workholding solution that can handle larger loads, tougher materials, and provide flexibility in their machining operations. Whether you work with aluminum, steels, titanium, or exotics, these fasteners are designed to meet your workholding needs with precision and efficiency. Elevate your CNC machining with this versatile and high-torque workholding solution.