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D4 Polyacrylite Helmet W/MIPS Shadow Olive

Troy Lee Designs

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The Reigning King of Full-Face Helmets

The reigning king of full-face helmets, the D4 range expands with a Polyacrylite model packing the same safety and comfort features as the premium carbon and composite models into a price-conscious shell. Details make the D4 the most coveted full-face in mountain biking, including Mips® C2 brain protection, an air intake system for ventilation, and an unmatched anatomical fit.

This helmet is designed and intended exclusively for use by bicycling activities, including mountain biking and off-road cycling.


  • MIPS C2 brain protection system-protects against rotational impacts
  • 3 Shell sizes and 3 EPS sizes, 6 total size ranges from XS-XXL
  • 24 total vents: 10 front intake ports, 5 overhead intake vents that channel air on top of your head and an industry leading 7 rear exhaust ports
  • EPP Collarbone impact system; a relief area that reduces the forces in the center lower section of the helmet where shoulder/collarbone impacts have been known to occur
  • 3-year warranty
  • CPSC 1203*, CE EN1078*, ASTM F1952-DH, ASTM 2032-BMX. *Varies by regional standards
    Size Head Circumference
    Small 55-56cm
    Medium 57-58cm
    X-Large 60-61cm
    2X-Large 62-63cm

    *Headliners and cheek pads can be interchanged within the same EPS size.