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 Hybrid.  Please refer to the general Head and Neck Restraint sizing chart below for proper 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 a Simpson® Hybrid™ Device Head and Neck Restraint System


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

  • A - Chest Circumference - Measure the chest CIRCUMFERENCE around the fullest part of the chest (pectoral muscles), keeping the tape semi-taunt.  Be sure there is NO slack in the tape and NOT tight.

MEASUREMENT NOTE: When possible, measure for a Hybrid™ with a driving suit on.  If a driving suit is NOT available, please add one (1) inch to final measurement.

Once this measurement is  completed, please refer to the sizing chart below to find the Simpson® Hybrid™ Device Head and Neck Restraint System that best fits your measurements.  

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

Simpson® Hybrid™ Device - Head & Neck Restraint Sizing and Fitment Chart***
 Factory Device Size
 A-Chest Circumference (in.)
22" to 24"
23" to 30"
32" to 36"
36" to 40"
40" to 44"
44" to 48"
48" to 52"

Simpson® Hybrid™ Device System Sizing Chart Note: Additional sizes may also be available. Please contact our Technical Sales staff for more information.


Simpson® Hybrid™ devices are manufactured in varied sizes (Child/Youth thru Adult Extra-Large).  There are five (5) models to choose from depending on the type of racing you do.  The most common models of Hybrid units for Sportsman racers are the Hybrid™ Pro, Hybrid™ Pro-Lite and Hybrid™ Sport.  The only differences are the base material construction and weight.  

Our chart below should help you decide exactly which unit suits you best.  However, we know it gets a bit confusing, so if you need help selecting your Simpson® Hybrid™ system, just contact one of Technical Sales Specialists for assistance.

Simpson® Hybrid™ Device - Model Applications for Head & Neck Restraint Systems***
Typical Racing Application
Hybrid™ Models
Model Notes
Jr. Dragsters - Quarter-Midgets - Mini-Wedges
Hybrid™ Sport
(Jr. Sizes)
Lightweight Design - Constructed of  Dupont® Carbon-Polymer Material
Car Club Racing Series and High-Performance Driving Schools (Designed to Fit Three (3) Point Factory Restraints)
Hybrid™ S
(Sizes XS - XL)
Lightweight Design - Constructed of Carbon Fiber Material
NASCAR® Approved (All Series Levels)
Approved for all Types of Race Cars and Motorsports Series
(Choice of Hybrid™ = Material, Weight & Design Preferred)
Hybrid™ Pro
(Sizes XS - XL)
Lightweight Design - Constructed of Carbon Fiber Material
Approved for all Types of Race Cars and Motorsports Series
(Choice of Hybrid™ = Material, Weight & Design Preferred)
Hybrid™ Pro Lite
Hybrid™ Sport (Adult)
(Sizes XS - XL)
 Pro Lite is Lightest Hybrid™ Unit Offered also Lowest Profile Design Available & Constructed of Carbon Fiber Material - Pro Sport is Constructed of  Dupont® Carbon-Polymer Material
Top Fuel - Funny Car - Pro Stock - Pro-Mod - Alcohol Dragster & FC - Top Sportsman - Top Dragster and any other thing Mind-Warpingly & Bad-Ass Fast
Hybrid™ X
(Sizes XS - XL)
Constructed of Carbon Fiber Material - Hybrid Pro Slide Head and Neck Restraint, Double Chin Strap "W" style and SFI 45.2 approved padding


IMPORTANT NOTE!  This is just a general overview of how Hybrid™ systems typically work.  Always refer to and closely follow the manufacturer's instructions for any safety device.


The tether assemblies for a Hybrid™ need to be adjusted to the individual driver, while seated in the racing position with all harnesses tightened.  Hybrid™ devices have TWO pairs of FHR tethers as shown in Figure 1 below.  The exact procedure to adjust these tether assemblies in the car should be done per the instruction manual provided with the Simpson® Hybrid™ system. Typically, the rear tethers should be adjusted first and then the front tethers would be adjusted next.

It is typically recommended to fit the tethers so that they will allow the Hybrid™ wearer forward head movement in the range of 25mm to 50mm (1" to 2") from the wearer’s Static or Starting position in the car as indicated in Figure 2 below.  Again - Always refer to the factory instructions manual.

DON'T FIND A FIT FOR YOU?  NEED A CUSTOM HYBRID UNIT? Simpson® Safety makes custom Hybrid™ units designed to your exact specifications and measurements to ensure a custom fit.  

If you require a Hybrid™ system made to your specifications, please contact our Technical Sales staff for a price quote and estimated delivery date.

TECHNICAL CREDIT AND ACKNOWLEDGEMENT: The above helmet and Hybrid® technical information and illustrations were compiled using excerpts from the Federal Internationale De L'Automobile (FIA) 'Guide and Installation Specifications for Hybrid™ 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 All of Your Racing Safety Gear Needs Covered

Please remember that Racecar Engineering™ carries a full assortment of all Simpson® Hybrid® Device Systems ranging from the Hybrid™ Sport all the way up to the Hybrid™ X, Hybrid™ S and Hybrid™ Pro series.  On top of that, we also have in stock and ready to ship, Simpson® 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 Simpson Safety/Hybrid™ 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.