Descriptions:  7mm Hex Shank Lengthen Core Drill Bit 16mm-25mm Woodworking Tools Hole Saw Cutter Hinge Boring Drill Bits.     Specifications:  Product Name: Core Drill Bit.  Bits Type: Extended thread.  Shank Type: Hexagonal shank.  Material: Cutter head: YG6 alloy.  Cutter body: 45 carbon steel.  Surface Treatment: Sprayed.  Purpose: Used for making holes in wood boards.  Size (optional): 16mm, 18mm, 20mm, 22mm, 25mm, 5-piece set (16, 18, 20, 22, 25mm).  Cutting Diameter: 16mm, 18mm, 20mm, 22mm, 25mm.  Total Length: 128.5mm, 129mm, 128.5mm, 129mm, 129mm.  Shank Diameter: 7mm.  Bit Length: 75mm, 76.5mm, 76mm, 74mm.     Features:  - 129mm ultra-long hole drill, which can support a variety of thickness wood board operations;  - YG6 material cutting head, high hardness, more durable;  - Contains the most commonly used cut-out sizes of 16-25mm.     Package Included:  Type: Quantity.  16mm: 1 Pc x 16mm Hole Saw Cutter.  18mm: 1 Pc x 18mm Hole Saw Cutter.  20mm: 1 Pc x 20mm Hole Saw Cutter.  22mm: 1 Pc x 22mm Hole Saw Cutter.  25mm: 1 Pc x 25mm Hole Saw Cutter.  5-piece set:  1 Pc x 16mm Hole Saw Cutter.  1 Pc x 18mm Hole Saw Cutter.  1 Pc x 20mm Hole Saw Cutter.  1 Pc x 22mm Hole Saw Cutter.  1 Pc x 25mm Hole Saw Cutter