Kaster C2 is the plainest Atom 2 SV MT builds: a matt anthracite shell shading into a lighter grey across the crown and flank, with ATOM in tonal lettering on the side and nothing else. It is the version bought by people who want the mechanism, not the graphic.

Why a modular helmet at all

A flip-up is a compromise, and it is worth being clear about which way it cuts before you buy one.

What you gain is specific and daily: you can lift the chin bar at a fuel stop without taking the helmet off, speak to someone at a barrier without shouting through a chin vent, wear glasses and put them on after the helmet, and drink a coffee without unfastening anything. On a long touring day those small frictions add up to a genuinely different experience.

What you give up is weight and a hinge. A modular shell has to carry a mechanism and the reinforcement around it, which is why this helmet weighs around 1,700 g against roughly 1,500 g for a comparable full-face. That is real, and it is felt after four hours rather than after four minutes.

About the Kaster C2 finish

Matt throughout. The lower shell and chin bar are a deep anthracite; from the vent line the crown lifts into a lighter grey, with a fine tonal pattern worked into the flank and ATOM set in slightly darker lettering. The visor mechanism cover and vent trims are black, and the MT logo sits small and grey on the side.

A tonal grey scheme is the hardest to photograph and by some distance the easiest to live with. There is no colour to clash with a jacket, no graphic to tire of, and matt hides the marks a modular helmet collects from being handled by the chin bar — which is how everyone picks one up.

ECE 22.06 and DOT

The Atom 2 SV clears the current European standard, mandatory since January 2024, and additionally carries DOT.

Against the 22.05 it replaced, the 22.06 tests 18 impact points instead of five, at several speeds, adds an oblique impact against an abrasive anvil measuring rotational loading, and applies a Brain Injury Criterion ceiling. For a modular helmet the standard also tests the chin bar and its latch, which is the part a flip-up has to prove and a fixed full-face does not.

The P/J question

ECE 22.06 marks modular helmets with a P (protective chin bar, ride closed), a J (jet, ride open) or both. MT does not publish which marking applies to the Atom 2 SV, and we are not going to guess on your behalf.

Practical consequence: ride it closed. The chin bar is designed to be lifted at a standstill — at a fuel pump, at a set of lights in a queue you are not moving in — not to be ridden with. If you specifically need a helmet approved for riding open, check the label inside the strap before you rely on it.

The chin bar mechanism

A single button under the chin releases the bar, and it can be operated with one gloved hand. The closure is MT-MDTC — a micrometric ratchet with a double hook, which is MT's answer to the objection that a ratchet fastened on one tooth can work loose.

Sun visor and nose deflector, aligned

The MT-ESP retractable sun visor drops from inside the shell, and MT aligned its lower edge with the top of the nose deflector.

That alignment is the detail worth noticing. On most helmets a dropped shade leaves a bright gap between its bottom edge and your nose, and low sun comes through it exactly where you are looking. Closing that gap is a small piece of engineering that you notice every time the sun is in front of you.

Pinlock in the box

A Pinlock DKS512 insert is supplied as standard, and the MT-V-35 screen is also compatible with the FogOff FOG013.

On a modular this matters more than on a full-face, because the temptation when a visor fogs is to lift the whole chin bar — which works, and which also means riding along with the front of your helmet in the airstream.

A chin curtain is fitted

MT supplies the chin curtain as standard rather than as an accessory. It closes the gap under the chin bar and cuts both the updraught and a fair amount of noise from below.

It is also removable in ten seconds, which is what you want in July.

The spoiler and ventilation

A rear spoiler hides the exhaust of a ventilation system MT developed with fluid-dynamics work, and translucent material is used in the vent pieces — a finish detail from a class above.

The spoiler is not styling. It creates the low-pressure region that pulls air out of the shell, and on a touring bike it also steadies the helmet in the turbulent air behind a screen, which is where most high-speed head-shake actually comes from.

Retention and interior

The lining is fully removable and washable, and MT builds the helmet so external parts detach individually for repair rather than requiring a replacement helmet.

On a 1,700 g helmet, wash the cheek pads regularly. A modular carries more lining than a full-face because the mechanism needs padding around it, and more lining holds more of everything.

What it does not have

• No independent safety rating. SHARP has not tested the Atom 2 SV; modular helmets are rarely in the programme, and there is no ADAC or Snell result.
• No published P/J marking — see above. Ride it closed.
• No tinted screen in the box; the internal shade covers most of it.
• It is heavier than a full-face. Around 1,700 g, and that is the price of the hinge.

In the box

• MT Atom 2 SV helmet — Kaster C2, matt anthracite and grey
• Protective bag, user manual and MT Helmets stickers
• Chin curtain fitted · Pinlock DKS512 insert supplied

Size guide

Specification

• Model — MT-Helmets Atom 2 SV · Part number — 1335E13C22 (XS–XXL: …03 to …08)
• Colour / finish — Kaster C2 — matt anthracite shading into grey
• Homologation — ECE 22.06 and DOT · P/J marking not published
• Safety rating — none; the Atom 2 SV is not in the SHARP database
• Type — modular / flip-up
• Shell — HIRP (High Impact Resistant Polymer), approx. 1,700 g
• Sizes — XS to XXL
• Visor — MT-V-35 · MT-FSOS fast opening · MT-ESLS release with vent position
• Anti-fog — Pinlock DKS512 included · FogOff FOG013 compatible
• Sun visor — retractable MT-ESP, aligned with the nose deflector
• Chin bar — single-button release, operable with one gloved hand
• Retention — MT-MDTC double-hook micrometric closure
• Chin curtain — fitted as standard, removable
• Interior — fully removable and washable
• Communication — intercom-ready; no system supplied
• Manufacturer — MT Helmets, Spain
• Fitting — measure above the brow at the widest point; between two sizes take the smaller
• Care — hand-wash the lining; never wipe the visor dry
• Replacement — after any impact, and after around five years regardless

• 1x MT Atom 2 SV helmet — Kaster C2 — matt anthracite shading into grey
• 1x protective bag
• 1x user manual
• 1x sheet of MT Helmets stickers
• Chin curtain fitted as standard
• Pinlock DKS512 insert supplied