This is a system I have been using for nearly 10 years, and is a great way to make consistent and accurate pacenotes.Its a simple disk system, with a pointer that determines the angle of your corner.
 
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The recce disk has many benefits:
Easy to install, taking around 10 seconds
Easy to change from car to car, and it’s fits into your rucksack.
A simpler method than tapping your steering wheel, which is time consuming and can leave residue on your hands after a day behind the wheel
The recce disk comes as a kit, ready to be fitted, including your straight ahead marker and Velcro to secure to your car