This is fitted into a standard 3/8 inch key or keyless chuck. Trend Snappy attachments or any direct drive 1/4 inch hex bits can then 'snap' in effortlessly. Ensures precise location in the chuck. A spring loaded outer sleeve makes it easy to remove attachments. Patent No. US5,398,946. For sale in UK and Eire only.S Dimensions: Chuck dia=23 mm Overall length=60 mm Shank Diameter=Centrotec Compatible Delivery=UK & Eire only Shank Diameter: Centrotec Diameter Metric: 23 Overall Length Metric: 60