1 mm, MPN: PEC12R-2225F-N0024.Bourns 24 Pulse Incremental Mechanical Rotary Encoder with a 6 mm Flat Shaft (Not Indexed), Through Hole, Encoder Signal: Digital Square Wave, Shaft Length: 15mm, Maximum Operating Speed: 100rpm, Mounting Hole Diameter: 1 mm, 2 x 2.