Seatylock Locks Compared 2026: Foldylock vs Mason vs Viking vs the New Ultra D5
Lay four Seatylock locks side by side on a table and they barely look related. A folding lock that packs into a slim case like a ruler. A matte-black U-lock with a red-tipped shackle. A chain wrapped in a black neoprene sleeve. And a heavy, armored U-lock the brand calls the first of its new Ultra series. Same company, same keys and code cards, completely different jobs.
Which one belongs on your bike depends on three trade-offs: how much security you need, how much weight you'll carry, and how much flexibility you want at the rack. Olivia Reviews compared Seatylock's full lineup on seatylock.com in October 2026, using the ratings, lengths and weights the brand publishes, to show where each family wins and where it gives ground.
Quick take: Mason U-locks give you Seatylock's top MLA level (Diamond) for the least money, from $75. Foldylocks ($80–$145) trade a little security for reach and frame-mounted convenience. Viking chains ($65–$125) wrap around awkward objects. The new Ultra D5 ($280) is the brand's answer to angle-grinder attacks. Before choosing, see today's Seatylock deals.
The Four Families at a Glance
| Family | Type | Price range | Top MLA level | Main strength |
|---|---|---|---|---|
| Foldylock | Folding plates | $80–$145 | Gold | Reach plus a rattle-free frame case |
| Mason | U-lock | $75–$90 | Diamond | Highest rating for the money |
| Viking | Chain | $65–$125 | Gold | Wraps odd-shaped posts and scooters |
| Ultra | Armored U-lock | $280 | Not stated on the listing | Built against angle grinders, per the brand |
A quick note on ratings: the Silver, Gold and Diamond levels come from a UK testing program run by the Master Locksmiths Association (MLA), and ART is a Dutch certification. Seatylock also prints its own security-scale numbers on listing graphics. Weigh the independent ratings first, as the brand's own FAQ suggests.
Foldylock: The Commuter's Middle Ground
Foldylocks are hardened steel plates riveted together so they fold into a compact bar and open into a loop. The family is wide, so here is how the models compare on the brand's own numbers:
| Model | Length | Weight | Ratings (per Seatylock) | Price |
|---|---|---|---|---|
| Clipster | 75 cm | Not listed | MLA Silver | $80 |
| Mini | 75 cm | 0.89 kg | MLA Silver | $85 |
| Compact | 85 cm | 1 kg | Silver; 14/18 brand scale | $95 |
| Foldylock 95cm | 95 cm | Not listed | Silver; 15/18 brand scale | $105 |
| Classic | 100 cm | 1.6 kg | Product page: Gold; FAQ: Silver | $125 |
| Forever | 90 cm | 1.76 kg | Gold and ART 3 stars; 18/18 | $135 |
| Elite | 110 cm | 1.9 kg | Gold and ART 3 stars; 18/18 | $145 |
Where Foldylocks win: reach. Even the 75 cm models give more room than a compact U-lock, and the 110 cm Elite goes around trees and railings. Every Foldylock also comes with a frame-mounted case that uses bottle-cage screws or included straps.
Where they give ground: no Foldylock reaches Diamond, and the Gold-rated models weigh close to 2 kg. Note the Classic's mismatch between its product page and FAQ if that rating decides your purchase.
Mason: The Most Rating per Dollar
The Mason series is where the numbers get interesting. Every Mason carries MLA Diamond, Seatylock's top independent level, and the FAQ adds ART 3 stars for the 140 and 180.
- Mason 140 ($75): compact and lightweight, with a triangular crossbar and double deadbolt.
- Mason 180 ($80): the brand calls it the world's lightest Diamond-rated U-lock, and its FAQ names it the balanced choice for most commuters.
- Mason 220 ($85) and 300 ($90): larger locking areas with a patented pentagonal crossbar, recommended for high-value e-bikes or overnight parking.
Where Masons win: security for the price. A $75 Mason outranks a $145 Foldylock on the MLA scale.
Where they give ground: a rigid shackle limits what you can lock to, and the $15 mounting bracket is sold separately.
→ Check the latest Seatylock coupon codes and deals
Viking: The Flexible Option
| Chain | Links | Ratings (per Seatylock) | 90 / 110 / 140 cm prices |
|---|---|---|---|
| Viking Silver | 7 mm square | MLA Silver; 12/18 | $65 / $70 / $80 |
| Viking Gold | 10 mm | MLA Gold; 17/18 | $100 / $110 / $125 |
The Viking Silver 90 weighs 1.35 kg according to its listing graphic. Both chains share a magnetic closure, an auto-shutter over the keyhole and a double-layer neoprene sleeve that Seatylock says cuts rattling.
Where chains win: shape. They go around lampposts with flared bases, fence posts and a scooter stem, and the FAQ says they suit light scooters.
Where they give ground: the Gold chain matches a Foldylock Forever's rating at a similar price, but you carry it over a shoulder or in a bag rather than in a frame case.
Ultra D5: The New Heavyweight
The Ultra D5 is the first product in Seatylock's Ultra series: a large U-lock that the brand says has "a very high resistance to Angle grinder attacks." Its listing graphic shows a 25 on Seatylock's own security scale, marked "Armored." In October 2026 the product page showed it at $280 with an add-to-cart option, while the description still said "Launch in November!" and "Save $45 on the product launch." Check the live page for current availability and whether a launch price applies.
Keep the brand's own caution in mind: its FAQ says "no lock can be completely grinder-proof." Higher resistance buys time, not invincibility.
Head-to-Head: Which Lock for Which Rider
| You need… | Best match in the lineup | Price |
|---|---|---|
| Maximum rating, minimum spend | Mason 140 or 180 | $75–$80 |
| Reach without a bag | Foldylock Compact or Classic | $95–$125 |
| A folding lock for an e-bike | Foldylock Forever or Elite | $135–$145 |
| Lock that clips to you | Foldylock Clipster | $80 |
| Odd posts or a scooter | Viking Silver or Gold | $65–$125 |
| Long stays where grinders are a worry | Ultra D5, ideally with a second lock | $280 |
What Every Seatylock Lock Shares
- Keys: three keys and a key code card. Register the code within 3 months to extend the 12-month warranty to 3 years.
- Shipping: free across the US, dispatched within 2 business days, with US delivery estimated at 4–7 business days.
- Returns: unused items in original packaging within 14 days of delivery, for a refund or store credit.
- Key-alike pairs: sold for several models, such as two Mason 180s for $155 or two Foldylock Elites for $285.
How to Save
Olivia Reviews found no public promo code on seatylock.com in October 2026. The real savings come from choosing the right family (a Mason costs less than any Foldylock), buying key-alike pairs for two bikes, and watching the Ultra D5's launch offer. For anything new, check the Seatylock coupon page.
Seatylock Comparison FAQ
Which is rated higher, a U-lock or a folding lock?
In Seatylock's range, the Mason U-locks carry MLA Diamond, while the top Foldylocks reach Gold. Folding locks offer more reach.
Which Seatylock is lightest?
Among the published weights, the Foldylock Mini at 0.89 kg. The brand calls the Mason 180 the lightest Diamond-rated U-lock.
Is the Ultra D5 available yet?
The product page showed a $280 price and an add-to-cart button in October 2026, but its text still referred to a November launch. Check before ordering.
Can two different locks share a key?
Only if bought together as a "2 units key alike" pack. Seatylock says it can't match a new lock to an existing key.
Final Verdict
Seatylock's lineup is easier to choose from once you see the pattern: Mason for the highest rating for the least money, Foldylock for reach and a lock that lives on the frame, Viking for awkward shapes, and the Ultra D5 for riders who worry about power tools. Match the family to where you park, then the size to your bike.
→ Compare today's Seatylock deals
Buying for two bikes? See current Seatylock offers before you pick a key-alike pair.
Olivia Reviews researched Seatylock using its official website, product listings and published policies in October 2026. We haven't personally tested these products. We may earn a commission when you buy through our links, at no extra cost to you.