4 mm Metric Hex Key helps replace a rounded or missing metric key before the socket in the fastener is damaged. The ISO 2936 width band is 4.00 / 3.95 mm, sized just under nominal so the key can enter an in-tolerance socket and bear on the flats.
Robotics and automation cells commonly keep dedicated metric keys near guards, tooling, sensors, and changeover points. This family supports the metric side of the catalog, including socket-drive cap screws, flat heads, buttons, shoulders, and set screws.
Review the 4 mm size and ISO 2936 max/min width data against the print before ordering. Keeping the driver as a loose single size helps replace the exact tool without buying a full set. The technical highlights below keep the verified width data separate from general application notes.
Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.
