As with all racing safety equipment, Head and Neck Restraint fitment is critically important, and the Head and Neck Restraint user can increase the risk of injury if they are not fitted properly.  A Frontal Head Restraint (FHR) restrains the driver’s head relative to the torso during a frontal impact, thereby reducing the loads to the head and neck.

There are different types of FHR systems approved, one of them being the Impact™ Accel™ system.  Please refer to the general Head and Neck Restraint sizing chart below for proper Impact™ Accel™ system fitment.    

This system sizing chart is for both ADULT and YOUTH devices.  If you need a Head and Neck Restraint system outside of this chart range, please contact our Technical Sales staff for other brand options that may be available for you.  

Properly Measuring Fitment for an Impact™ Accel™ Head and Neck Restraint System


Locate a cloth tape measure and record the following body measurement:

  • A - Neck - No measurements needed!  One size fits all! 

The Impact™ Accel™ Head and Neck Restraint System comes in two (2) sizes.  One Standard size for adults over 100lbs and one Small Size that best fits most youths.  

Remember, if you DO NOT find a Head and Neck Restraint System that suits you or fits you properly, please contact one of our Technical Sales Specialist and they will work with you to find a solution for you.

Impact™ Accel™ System - Head & Neck Restraint Sizing and Fitment Chart***
 Factory Device Size
 A - No Measurement Needed
Small Size
Standard Size System Fits Most All Adults Over 100lbs


Impact™ Accel™ devices exist only in two sizes (Standard and Small) and each system is adjustable to driver and seat configuration, as the Impact™ Accel™ system is fully adjustable from 10 degree to 40 degrees.

When a driver is seated in the racing position with the harnesses tightened, the Impact™ Accel™ collar angle must be between 60° and 90° from the horizontal (see Figure 1 and Figure 2 below).

The Impact™ Accel™ system may lightly contact helmet, but if the Impact™ Accel™ collar angle is higher than 90° from the horizontal (the top of the collar is pointing forward instead of pointing backwards), an adjustment will be required (for example from a 30° Accel™ system angle to a 20° Accel™ system angle).

The Impact™ Accel™  system may lightly contact the seat or head rest, but if the Impact™ Accel™ system pushes the head forward uncomfortably, the Impact™ Accel™ collar top goes backwards in an angle from the horizontal lower than 60°, an adjustment to a higher angle may be required (for example from a 20° Accel™ angle to a 30° Accel™ angle).

The Figure 3 drawing below shows all typical seat angles that the Impact™ Accel system will easily accommodate.

Impact™ Accel™ System - Model Applications for Head & Neck Restraint Systems***
Seat Angle
Typical Racing Application
Applicable Accel™ Model
Jr. Dragster - Micro-Sprints - Mini-Wedge - Quarter Midgets
The Impact™ Accel™ Small System is Intended for Youths and is an 'Adjustable' Model - Allows Adjustment from 10 to 40 Degrees.


Each Impact™ Accel™ System Works with All Types of Race Cars and Various Seat Configurations: This includes Sprint Cars - East Coast Modifieds - Asphalt Late-Models - Dirt Late-Models - Street Stocks - Legends - IMCA/UMP/Wissota Modifieds - Full-Bodied Drag Cars and Dragsters - Sedan Sportscars - Drag Boats - Open Wheel/Road Race Cars including Formula Ford®, Formula Mazda®, Barber Dodge® and Infiniti® Pro
 The Impact™ Accel™ Standard System is an 'Adjustable' Model - Allows Adjustment from 10 to 40 Degrees.

Standard Size Model Fit Most Most Adults Weighing 100lbs or Greater

TECHNICAL CREDIT AND ACKNOWLEDGEMENT: The above FHR, seat and helmet technical information and illustrations were compiled using excerpts from the Federal Internationale De L'Automobile (FIA) 'Guide and Installation Specifications for FHR Devices in Racing Competition' document published in June 2017.  To review this full PDF document click here or visit the FIA website Safety Section at (both links open new browser window).

Racecar Engineering™ Has Your Racing Safety Gear Needs Covered

Please remember that Racecar Engineering™ carries a full assortment of all Impact™ Accel™ Systems. On top of that, we also have in stock and ready to ship, Impact™ Safety driving gloves and shoes, underwear, hoods, socks, helmets, harness pads, seat belt restraints, helmet skirts, gear storage bags and much more.

Browse our wide selection of safety products and buy online today.  If you have questions about choosing the right safety equipment for your motorsports segment, please contact one of our Technical Sales Associates for assistance.

At Racecar Engineering™ we make every attempt to be every racer's 'One-Stop Safety Shop'.

Return To:  Main Technical Center Page  |  Head and Neck Restraint Info/Sizing Chart Page - All Brands

Related Tech Safety Topics:  Racing Helmets | Racing Suits | Driving Gloves | Driving Shoes | Racing Seats

*** HEAD & NECK RESTRAINT SYSTEM SIZING/FITMENT CHART DISCLAIMER: This head and neck restraint system sizing/fitment chart has been created by Racecar Engineering™ for our customer's reference and ease-of-use using the latest fitment information available from the factory.  Please always refer to the factory website, factory printed materials and factory personnel advice for the latest head and neck restraint system information about their brand of safety product.  The Impact Racing Products factory website can be accessed directly at (link opens new page) - Racecar Engineering™ is not responsible for any typographical errors contained in this head and neck restraint system sizing chart/fitment material or the end-user's failure to verify & follow factory fitment specifications.