FLOW's four-layer micro-engineered insert cuts concussive linear impact and slides in beneath a rotational slip-liner like MIPS — cold-stable protection in a sub-10mm profile built for the mountain.
Key statistics
Standard helmet foam is designed to prevent skull fractures and death — not the 70–120 G impacts responsible for the vast majority of ski concussions. Helmets can pass every safety certification and still leave your brain unprotected.
Engineered to disappear
into your helmet.
FLOW is built to sit alongside a helmet's existing rotational slip-liner — like MIPS — not replace it. It hands rotational protection to that liner and focuses on what a slip-liner doesn't do: cold-stable linear energy management and comfort. A graded, geometry-driven lattice is the primary absorber, the temperature-sensitive layer stays thin and out of the main load path, and the outer facing gives the slip-liner a clean surface to slide against.
PTFE Low-Friction Glide Facing
A controlled low-friction PTFE facing on the helmet-facing surface. Rather than competing with the helmet's rotational slip-liner, it gives one a clean, cold-stable surface to shear against — so a slip-liner such as MIPS keeps its full ~10–15 mm of rotational travel while FLOW works beneath it. On helmets without a slip-liner, the same facing still provides a baseline slip plane.
LT-EPU Graded Auxetic Lattice
Low-Temperature Elastomeric Polyurethane 3D-printed into a functionally-graded, auxetic (negative-Poisson) micro-lattice — soft head-side cells firming toward the shell. Because its response is geometry-driven, it stays elastic to −55°C and does not cold-drift. The grading flattens the force plateau, so it soaks more energy at a lower peak G than a uniform lattice.
Silicone Interface Film
A paper-thin silicone elastomer film that bonds the LT-EPU lattice to the comfort foam beneath and routes energy between them. Maintains full flexibility to −60°C, where TPU begins to stiffen around −30°C.
Rate-Sensitive Comfort Foam
A thin cold-validated non-Newtonian foam (Poron XRD-class) against the head — soft and conformable at rest, firming under load for fit and final energy trim. Kept deliberately thin and secondary, so the temperature-sensitive layer never sits in the primary load path.
Every layer earns its place in the stack. From the helmet shell to your head — nothing wasted.
FLOW insert — four layers from outer to inner: PTFE low-friction glide facing · graded auxetic LT-EPU lattice · silicone interface · rate-sensitive comfort foam. ~9mm total, and it slides in beneath a rotational slip-liner such as MIPS.
FLOW's layered architecture manages linear energy across the entire duration of an impact — and pairs with your helmet's own rotational slip-liner (such as MIPS) for rotational protection, not just the peak.
Glide facing works with your slip-liner
On any angled impact, rotational protection is handled by the helmet's own slip-liner (such as MIPS). FLOW's outer PTFE facing gives that liner a clean, cold-stable surface to shear against — so it keeps its full rotational travel and FLOW never competes with it. On a helmet without a slip-liner, the facing still offers a baseline slip plane.
Graded auxetic lattice takes the primary load
The geometry-driven lattice compresses progressively under G-load; its graded, auxetic cells draw material toward the impact and flatten the force plateau, soaking the bulk of the energy at a lower peak G. Because the response is structural — not viscoelastic — it does not cold-drift, staying elastic to −55°C.
Silicone interface routes energy
The cold-stable silicone film transmits remaining energy smoothly to the comfort foam below, maintaining insert integrity across repeated impacts without stiffening in cold conditions.
Comfort foam trims the remainder
The thin inner non-Newtonian foam is soft against the head at rest and firms under load — trimming the last of the energy and dialing in fit. Kept deliberately thin and secondary so the temperature-sensitive layer never carries the primary load.
FLOW works with your helmet's rotational slip-liner, not against it: its low-friction facing gives a slip-liner such as MIPS a clean, cold-stable surface to rotate against — so a maker keeps whatever rotational system they already use and adds FLOW's cold-stable linear and comfort protection beneath it.
FLOW is an independent product and is not affiliated with, sponsored by, or endorsed by MIPS AB. MIPS is referenced only to describe compatibility.
Built from the inside
of an ICU.
FLOW was not invented in a lab. It was engineered from a lived experience — a 14-year-old park and big mountain skier, a traumatic brain injury on a mountain he loved, and a year-long recovery that exposed exactly what the helmets on everyone's heads were failing to do.
A family shaped by the slopes
For the Lin family, mountains are more than a backdrop — they are a way of life. Charlie's father, Albert Lin, is a National Geographic Explorer and TV host who found freedom and renewal on the slopes after losing his own leg in an accident. He passed that passion directly to his children.
Charlie grew up as a park and big mountain skier at Mammoth, where hitting jumps, riding features, and charging lines shaped his sense of self. From Mammoth to Niseko to Palisades Tahoe, skiing was the heartbeat of the family.
Home mountain: Mammoth. Charlie grew up logging thousands of hours on the same features and lines that would later change his life.
"This isn't a story about getting back to normal. It's about redefining what it means to live after your world has ended once already — and using that transformation to build something that protects the next person on the slope."
— Charlie Lin, Founder & CEO, FLOWWaking up and not knowing who you are
An accident on the slopes of Mammoth sent Charlie to the ICU. He woke from a coma not knowing how to walk, breathe on his own, or who he was. In an instant, the mountain that had given him everything demanded everything back.
What followed was a year inside the science of traumatic brain injury — neuroplasticity, recovery, the limits of the human brain, and the community of people who refused to let him disappear into the void.
TBI is a silent epidemic. The long-term effects — depression, identity loss, cognitive impairment — are often stigmatized or ignored, especially in young athletes.
Helmets save lives. They don't prevent concussions.
During his recovery, Charlie dove deep into brain injury science. He had been wearing a MIPS helmet — and MIPS likely saved his life. But he still ended up in a coma. If the helmet did its job, why was he in an ICU?
The answer: helmets are certified to prevent skull fractures and death, not concussions. The EPS foam in virtually every ski helmet is engineered for catastrophic high-G events. The 70–120G range responsible for the vast majority of concussions falls into a protection gap the entire industry has accepted as normal.
Throughout his recovery, Charlie and his father raised Monarch butterflies — a symbol of transformation. He was not returning to who he was. He was becoming someone new.
"My father lost his leg and found the mountain again. I lost my memory and found my purpose. FLOW exists so that someone else's kid doesn't have to find either the hard way."
— Charlie Lin, Founder & CEO, FLOWEngineering the answer
FLOW is Charlie's answer to what he survived. Not a replacement for your helmet — an insert that works alongside it, filling the protection gap that certified helmets leave open. A four-layer system tuned to the 70–120G concussion range.
The insert is thin enough to wear in any compatible helmet. Light enough that you forget it's there. Cold-rated to −40°C because the mountain doesn't wait for warmer conditions.
Protection that comes from experience, not a spreadsheet.
Every layer in FLOW's insert was chosen because someone who has been inside a TBI recovery knew what was missing. That's not a marketing line — it's why the physics is right, why the cold rating matters, and why the rotational slip layer is on the outside where it belongs.
Whether you're a helmet manufacturer, investor, or athlete — we'd love to talk.
"Concussion awareness isn't new, we're just finally building technology that respects it."— Charlie Lin, Founder