This is a tool set primarily used for opening and closing the case backs of watches, especially those with grooved cases for water resistance. I no longer need it, so I'm putting it up for sale. It has never been used. Product Description • Purpose: Designed for opening and closing the case backs of waterproof watch cases. Especially suitable for grooved case backs. • Set Contents: • 6 Chucks: Each chuck corresponds to a different diameter, applicable to various watch case sizes (diameters from 18.50mm to 29.50mm). • No.0: Ø18.50mm • No.1: Ø20.20mm • No.2: Ø22.50mm • No.3: Ø26.50mm • No.4: Ø28.30mm • No.5: Ø29.50mm Handle: Designed for a firm grip, allowing for efficient force transmission. Features • High Precision: The chucks are precisely designed to safely open and close watch case backs. • Multilingual Instructions: Usage instructions are provided in French, German, English, and Spanish. • Durable Material: Made of durable metal, suitable for long-term use. This type of tool is ideal for watch repair shops and those who enjoy maintaining their watches as a hobby.