Think All Tiny Compasses Are Useless? Think Again – Polymath Products NV-20K Pocket Compass Review

Whether you're a seasoned navigator or just starting out on your outdoor journey, having a reliable backup compass is essential. The NV-20K Pocket/Zip Compass by Polymath Products is exactly that — a compact, tough, and surprisingly accurate navigation tool designed to perform when your electronics don’t. It may be small, but it’s built to handle the kind of punishment and conditions many of us face in the field.

Polymath Products NV-20K Pros & Cons

Pros

• Extremely compact and lightweight

• Accurate when held flat

• Glows in the dark – compass dial and rear 'lamp'

• Excellent build quality – no flex, rugged feel

• Shockproof, oil-sealed, and waterproof to 80m

• Ideal backup or EDC compass

• Great value for money

Cons

• Needs to be held completely flat for best accuracy

• Can be easily affected by nearby electronics/metal surfaces

• Lacks direction-of-travel markings for more complex navigation

• Glow must be "charged" with a light source (not a con for everyone)

UKSN Rating: ★★★ (3/4)

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NV-20K Pocket Compass Overview & First Impressions

Right out of the packaging, the NV-20K impresses with its solid, no-nonsense design. It has a reassuring feel to it — lightweight but not flimsy, with zero flex in the casing, thanks to its rugged, oil and seawater-resistant TPU body. At just 6g, and measuring 35mm x 27mm x 13.5mm, this little powerhouse will sit comfortably on a zip pull or keyring without getting in the way.

You can tell it’s not just a toy or a novelty item. The finish, materials, and construction all give off the impression that this compass was made with real-world use in mind — and it absolutely was.

Performance & Accuracy

Let’s address something straight away — accuracy. Many of you likely know this already, but it’s crucial that this compass is held flat to get a reliable reading. During testing, we found that when laid next to tech devices or metallic surfaces, the reading could be completely thrown off — but in the field, where that interference isn’t present, the NV-20K performs admirably.

In fact, for such a small compass, its 20mm diameter luminous dial is surprisingly precise. The needle re-centres quickly when held flat and given a slight shake — another useful trick to keep in mind when confirming a heading.

This is not your average "button compass" — the kind you might find on a survival bracelet or keyring. The NV-20K stands apart in terms of both quality and capability.

Night Use & Photoluminescence

One of the standout features of the NV-20K is its dual photoluminescent system. Not only is the compass dial glow-in-the-dark (charged by light), but it also has a soft-glow 'lamp' on the back. This lamp is ideal for reading maps or marking your position in low-light conditions.

The glow isn’t overbearing, so it won’t ruin your night vision, and it recharges quickly with just a few seconds under a torch. For dusk-to-dawn adventures or emergencies, this is a brilliant bonus feature!

Durability & Construction

This compass is military-grade shockproof and oil-bath sealed, giving it fantastic resistance to vibrations, drops, and impacts that would easily compromise cheaper alternatives. The oil-filled chamber not only improves damping and needle stability, but also protects the internals from harsh external conditions — a crucial feature for real-world use.

Built from non-metallic, non-magnetic, and seawater-resistant TPU, the NV-20K isn’t just rugged — it’s almost indestructible. The materials used ensure it won't corrode, degrade, or interfere with the compass's accuracy, even after prolonged exposure to salt, moisture, or extreme environmental changes.

It operates reliably in temperatures ranging from -30°C to +50°C and is rated for pressures up to 9 atmospheres — meaning it can function at altitudes and depths far beyond what most people will ever encounter. You could literally take it scuba diving down to 80 meters if you wanted to. Not that you’d use it underwater for navigation, but it’s a strong testament to the engineering behind it.

Whether you're hiking through a storm, paddling coastal waters, navigating dense forests, or stuck in a whiteout at altitude, this compass is built to endure the type of abuse that most other tools simply won’t survive.

Everyday Carry & Versatility

Thanks to the 60mm loop cord (120mm total), the NV-20K is easy to keep on your person. Clip it to your jacket zip, bag, keys, or anything else you can think of. It’s the kind of tool you can just carry every day without thinking about it, and when the time comes, you’ll be glad it’s there.

It's an ideal backup to a primary compass or GPS — especially since tech can fail due to dead batteries, bad weather, or signal issues. This doesn’t.

NV-20K Pocket Compass Final Thoughts

The NV-20K Pocket/Zip Compass is a brilliant piece of kit. It’s everything a backup compass should be: tough, lightweight, unobtrusive, and dependable. The accuracy is surprisingly good for its size — just make sure you use it correctly by keeping it flat and away from tech.

It's one of those tools you’ll forget you’re carrying — until you need it. And when you do, it won’t let you down.

The NV-20K Pocket/Zip Compass comes highly recommended as part of any everyday carry, survival tin, or backup navigation setup. Plus, its costs under £10! What more could you want? This is why this tiny compass from Polymath Products earns our Gold Tried and Tested Award.

Save 10% on Your Polymath Products Order!

Thinking of picking one up? You can save 10% on any order directly from Polymath Products by using our exclusive code: UKSN

Whether you're upgrading your kit or buying your first mini compass, a little discount goes a long way. Plus, you can feel good about supporting a small independent British company!

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🎁 Win a NV-20K Pocket Compass!

Want to get your hands on a Polymath Products NV-20K Pocket Compass for FREE?

We regularly give away gear in the UKSN community—and this could be your chance! To enter:

Comment on this blog post sharing your favourite NV-20K feature.

It’s quick, easy, and open to all UKSN members (free & paid). Don’t miss out - you could be testing one of these yourself on your next adventure.