The guided fall equipment specified in M2010 is estimated to be as much as 20% more severe for equal velocities than the free drop device specified by ECE R22-05. And M2010 then demands a second impact at the same site looking for a substantial margin of impact management capability beyond what was exhausted in the first strike. Helmets without this margin or, for any reason unable to withstand multiple impacts cannot pass this test. 
In addition to a flat impact surface, both standards call out aggressive impact surfaces which concentrate impact stresses in order to punch through a relatively small area of the helmet to the wearers head inside. A helmet must combine a rigid outer shell with a sufficient wall thickness in order to meet test requirements. However, ECE R22-05 substitutes a kerbstone surface for the hemisphere called out in M2010 and also in the United States DOT-FMVSS218 and BSI 6658-85. This kerbstone is better suited to free drop testing but is not nearly as aggressive as the hemisphere. Taken together, the differences between guided-fall and free drop testing, the double impacts and the more aggressive hemispherical anvil imply that M2010 impact testing is as much as 50% to 100% more severe than in ECE R22-05.

Different impact points
Whether helmet is tested with selected site or anywhere above test line ECE R22-05 requires impact tests at several designated locations on the helmet surface. 
M2010 allows testing anywhere on or above a given test line and demands that test technicians conduct testing in the manner most likely to produce a failing result. The broad range over which impacts may be applied assures that M2010 impact management capabilities are not limited to isolated spots on the helmet.

SNELL M2010 drops a 3 kg steel striker with a sharp conical point from a 3 m height onto any site on the helmet shell above the test line. The striker must not penetrate the helmet to contact the test headform. All parts of the shell above the test line including ventilation holes are subject to this shell penetration test.

Two-time impact for the same impact point
In addition to demonstrating a superior of impact management capability, the M2010 double impact protocols also seek to determine whether a helmet might continue to protect its wearer for an entire crash event. A motorcyclist must survive the first spill from the bike and then all the considerable tumbling, bouncing and sliding that is likely to follow. The same helmet must protect throughout.

About ECE 22.05
The Economic Community of Europe (ECE) is actually the most commonly used helmet standard internationally with ECE 22.05 required by over 50 countries worldwide.  

About Snell
William "Pete" Snell (was a popular amateur sports car race driver who was killed in a crash in 1956. He died of massive head injuries when the auto racing helmet he was wearing failed to protect his head.

As a memorial to Pete, a group of scientists, physicians, racing colleagues and friends teamed together in a dedicated effort to promote research, education, testing and development of standards geared to improve the effectiveness of automotive racing helmets. Through their work, the Snell Memorial Foundation was established in 1957.  

Today, Snell is known for its ongoing work in setting, maintaining and continually upgrading the most authoritative helmet standards in the U.S. and throughout the world. Snell tests thousands of helmets each year and maintains its objectivity by remaining independent of helmet manufacturers, as well as local and national governments. Its state-of-the-art testing facility is located in North Highlands California, just outside Sacramento.