Anti-Camout Ribs.

Ironically, Phillips screws were designed to cam out. They were invented to prevent unskilled industrial workers from overdriving fasteners. The tapered wings of Phillips drivers act as a clutch that forces drivers out of screw sockets after the screws are driven home. But the tradeoff is that workers have to lean hard on the drivers to prevent unwanted slippage.

In case you didn't know, ACR stands for the "anti-camout ribs" that are formed on Phillips driver tips and may also occur in screw sockets. The ribs mate drivers securely to screws to minimize camout while reducing worker fatigue. ACR drivers can reduce camout by 30% to 40%.

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