Black Diamond Cosmo 350 (BD620751)
Published · Researched 2026-09-21
2026 lineup note: The Cosmo 350 is Black Diamond's dual-fuel generalist: 350 lm, 79 g on AAA / 73.5 g on the BD 1500 battery, IPX8. MSRP $39.95 on blackdiamondequipment.com (observed out of stock on BD's own site 2026-09-20); street $24.59–$39.99. The separate Cosmo 350-R (integrated rechargeable, 375 lm, IP67) is a different product — don't mix their specs.
Version lineage (2023–2026)
- 2020: Cosmo 350 replaces the Cosmo 300 with the current platform: dual-button UI, second button for lens selection, multifaceted optical lens, IPX8, dual-fuel (3× AAA included / BD 1500 rechargeable sold separately), digital lock, integrated battery meter.
- 2023–2026: No generational change observed; still the current Cosmo as of Sept 2026. Running color updates only.
- Sibling: Cosmo 350-R (rechargeable-only, 1500 mAh Li-ion, micro-USB, 75 g, IP67, 375 lm high) — launched alongside the -R headlamp refresh wave; different battery system, not dual-fuel.
- Discontinued predecessors: Cosmo 300, original Cosmo. Old Cosmo 300 stock still appears at discount — it's 50 lm dimmer with the older single-button UI.
- Smart-buy advice: The rechargeable BD 1500 battery is sold separately (~$30–40 historically — UNVERIFIED current price); if you'll use the lamp often, do the bundle math against the Cosmo 350-R or the Spot 400-R.
Overview
The "keep it simple" BD headlamp: 350 lumens, dual-fuel power, red night vision that activates without cycling through white light, a digital lock, and a battery-percentage meter — all IPX8 waterproof. The second button (lens/mode selection) was the big usability upgrade over the old single-button Cosmo. It sits between the Astro (simpler) and the Spot (brighter, more featured) in BD's lineup, and its dual-fuel design makes it the natural pick for backpackers who want alkaline backup on long trips.
Key Specs
| Spec | Value |
|---|---|
| Max output | 350 lm high · 175 lm medium · 6 lm low |
| Beam distance | 64 m high · 45 m medium · 10 m low |
| Burn time | High 3 h (AAA) / 5 h (BD1500) · Medium 6/10 h · Low 200/225 h |
| Weight | 79 g (3× AAA, included) · 73.5 g (BD1500, sold separately) · 46 g without batteries |
| Power | Dual-fuel: 3× AAA (included) or BD 1500 Li-ion (sold separately) |
| Water resistance | IPX8 (tested 1.1 m for 30 min; water may enter battery compartment — dry fully after wet use) |
| Modes | Proximity + distance, dimming, strobe, red night vision (dimming + strobe), digital lock |
| Extras | Integrated battery meter (% display), recycled elastic Repreve headband, multifaceted lens |
| SKU | BD620751 |
Sources: blackdiamondequipment.com official product page; locally.com, epictv.com, skyviewcamping.com listings (all observed 2026-09-20).
Long-term durability
- BD headlamp housings are generally multi-season durable; the Cosmo's sealed IPX8 body handles rain and river crossings well.
- Known weak points from owner reports on the 350 platform: the battery-door latch and the AAA contact springs if alkalines are left in over winter (same alkaline-leakage warning as every AAA lamp). Dry the battery compartment fully after any submersion — BD's own copy warns water may enter it.
- The digital lock is the anti-failure feature: accidental pack activation (and the resulting dead lamp) is the #1 "failure" of simpler headlamps.
- BD warranty is 3 years (per BD's published policy; current claim turnaround not re-verified — UNVERIFIED).
Pricing
- MSRP: $39.95 — SOURCE: blackdiamondequipment.com (observed 2026-09-20; marked "Sale Out of Stock" on BD direct — buy from retailers).
- Street: $24.59–$39.99 — SOURCES: epictv.com "as low as $24.59" (reg. $33.23); locally.com $29.96–$39.99; skyviewcamping.com $44.95 (temp. out of stock). Prices vary by color.
- BD 1500 battery + charger are separate purchases (current price not re-verified — UNVERIFIED).
In the Box
- Cosmo 350 headlamp
- 3× AAA batteries
Warranty
3 years — Black Diamond's published warranty. Exclusions and current claim turnaround not re-verified in this pass (UNVERIFIED).
Support & Parts
- Black Diamond Equipment (Salt Lake City, UT). BD 1500 batteries and chargers are the relevant spares; replacement headbands available through BD and retailers.
Head-to-head vs closest rivals
- vs Black Diamond Spot 400-R (
black-diamond-spot-400-r): Spot 400-R is brighter (400 lm) and rechargeable-native. Cosmo 350 wins on price and AAA dual-fuel flexibility — pick Cosmo for long trips away from outlets. - vs Black Diamond Astro 300-R (
black-diamond-astro-300-r): Astro 300-R is simpler (single button, 300 lm, IPX4) and rechargeable-only. Cosmo 350 adds red night vision, IPX8, and dual-fuel for ~$5 less street. - vs Petzl Tikka (
petzl-tikka): Near-direct rivals at the same price tier. Cosmo: IPX8 + dual-fuel + battery meter. Tikka: Petzl's 5-year warranty + CORE upgrade path + pouch-lantern. - vs Fenix HM23 v2.0 (
fenix-hm23-v20): HM23 is the AA-enthusiast pick (IP68, magnetic tail, detachable). Cosmo is lighter and has red night vision.
Care & maintenance
- After any submersion or heavy rain, open the battery compartment and dry completely — BD's own spec warns water may enter it.
- Remove AAA batteries for off-season storage.
- The lock mode is engaged via the digital lock sequence — use it; it prevents the classic dead-in-pack failure.
Buying traps
- Cosmo 350 vs Cosmo 350-R: the -R is integrated-rechargeable (375 lm, IP67, micro-USB) and NOT dual-fuel. Different battery system, different product.
- PFAS shipping restriction: BD's own site notes the Cosmo 350 "cannot be shipped to California, New York, or Colorado" due to PFAS content — buy from a local retailer in those states if needed.
- Cosmo 300 old stock: looks similar, single-button UI, 300 lm. Verify "350" on the packaging.
- BD direct was out of stock at observation — retailers (REI, Backcountry, local shops) are the reliable channel.
Community Verdict
The consensus "safe default" BD headlamp for camping and general hiking: bright enough, genuinely waterproof, simple UI with the red-light shortcut that preserves night vision, and dual-fuel for trips away from charging. Owner criticism clusters around the BD 1500 battery being a separate purchase (the rechargeable story costs extra) and the battery-meter accuracy on alkalines. At street prices under $30 it's one of the best value-per-lumen headlamps in the catalog.
Images
images/black-diamond-cosmo-350-1.jpgimages/black-diamond-cosmo-350-2.jpgimages/black-diamond-cosmo-350-3.jpgimages/black-diamond-cosmo-350-4.jpg— Cosmo 350 blue colorway, side viewimages/black-diamond-cosmo-350-5.jpg— Cosmo 350 graphite, 3/4 view with controlsimages/black-diamond-cosmo-350-6.jpg— Cosmo 350 camo/green, large front view
Research date: 2026-09-20. Specs/prices change; re-verify live before buying. Claims dated above; anything marked UNVERIFIED was not confirmed from a primary source.