Safety standards are an essential part of auto racing.
Safety standards offer a required guaranty of basic protection to the various participants (drivers, crew, track personnel, rescue team...). Sanctioning bodies or specialized non-profit entities establish safety standards and the tests a product must undergo to earn their safety label. Such tests consist in timed flame exposure, applied pressure on a product or its components, resistance to various impact types from different angles… Samples of each product (according to size, options, etc.) are sent by the manufacturers to test laboratories approved by the sanctioning bodies, certification being granted if the given product exceeds the required standards. Here is a summary of the most commonly used and most stringent standards for the FHR system:

Extracts from the FIA rules:
Wearing a head restraint approved by the FIA will be mandatory for all drivers and
co-drivers in international events.
Be careful! Check with the federation governing your championship: decisions to make the FHR System mandatory can be very sudden and it is not advisable, in terms of comfort and safety, to install the FHR System at the last minute or in a short notice without a professional.
          FIA 8858-2010 
SFI Spec 38.1
Where required
FIA: Used in FIA sanctioned races in Europe, Australia and Asia.
SFI: Used in most racing events in U.S.A. and Canada run under SFI standards.
Validity period
No expiration date for head and neck restraint systems sporting FIA 8858-2010 standard.
For advice regarding head-retention devices meeting SFI standard 38.1, contact Stand 21 North America
More info
You will find herein all possible setups combinations FHR - tethers - post anchors – helmets, following the newly released FIA 8858-2010 Frontal Head Restraint (FHR) standard.
For reading this matrix, you can either start from the FHR / thethers (on the left side of the matrix) or start from the helmet - post anchors (on the right side of the matrix), the arrows show that any combinations allowed on the left side can be used with any combinations allowed on the right side (and vice versa).