This is a watch built almost entirely out of things you can't see.
The moonphase disc in the sub-dial at 2 o'clock turns through the lunar cycle, so what's showing today isn't what was showing a fortnight ago — and at new moon it slips behind the mask entirely. There's a hidden line from a comic strip printed across that mask, invisible until you put the watch under ultraviolet light, at which point the whole scene lights up blue while the hands and indexes glow green. Even the battery cover on the back carries a detail, and that faces your wrist.
Which leaves exactly one surface that is on show every second of every day: the strap. Here's how to choose it.
The size: 20mm
Every MoonSwatch takes a 20mm strap. Every mission, no exceptions — the Moonphase included.
And the thing worth knowing before you shop: our mission collections are a colour menu, not a compatibility list. Every MoonSwatch strap we make is 20mm with the same 126mm and 78mm lengths, cut for the same 42mm case. A strap filed under New Moon or Mars fits your Snoopy exactly as well as one filed under Moonphase. Buy for colour, not for the label on the collection.
The most wanted MoonSwatch, and what that does to the strap question
The Moonphase arrived in March 2024, two years into the collaboration, and it did something none of the earlier missions had: it added a complication. The sub-dial at 2 o'clock became a moonphase, with the tips of the moons pointing to numerals around the sub-dial edge that tell you where you are in the lunar cycle. The cartoon detail on the disc is what made it the most sought-after release in the range — boutique-only, one per person per day, and trading well above list almost immediately.
The rest is standard MoonSwatch and none the worse for it: a 42mm asymmetric Bioceramic case in white, the tachymeter bezel with the "dot over 90" borrowed from the Speedmaster, three recessed sub-dials, two pushers flanking the crown, and a quartz chronograph. Bioceramic is Swatch's own material — two-thirds ceramic, one-third biosourced from castor oil.
Here's the consequence for the strap, and it's specific to this reference rather than the range. This is the MoonSwatch people keep. It isn't the one you throw in a bag for a beach week; it's the one that gets looked after. And the factory Velcro is the single component on the watch with a shelf life — it fuzzes, it holds lint, it greys, and unlike the case it was never meant to last. On a watch you intend to still own in five years, the strap is the only part whose condition you actually control.
Two practical notes while you're changing it. Bioceramic is hard but it marks more easily than steel, and a monobloc case can't be sent away for a tidy-up — so work on a soft cloth, keep the spring-bar tool square to the bar, and keep metal away from the case flanks. On a white case, a slip shows twice as much.
The best straps for the Snoopy Moonphase
1. White with a black line — the watch's own two colours
Look at what the watch is actually made of: a white case, a white bezel, and black hands and lettering. That's the whole palette. A white strap with a black line repeats it exactly, which makes the strap read as part of the design rather than an addition to it — and the black line does the same job below the case that the hands do above it. It's the most finished this watch looks, and it's where I'd start.
2. White on white — let the sub-dial be the only event
The purist option. A tone-on-tone white strap turns everything from lug to buckle into one continuous white object, which leaves the moonphase sub-dial as the single thing happening anywhere on your wrist. On a watch whose entire appeal is one small rotating detail, that's not a small thing — it's the configuration that makes people lean in and look.
3. Plain white — the version that stays playful
The simplest of the three and the one to reach for if the black line feels too formal. A plain white rubber strap keeps the watch light, bright and unserious, which is the register the whole design is pitched in. It's also the easiest to live with in summer, and it wipes clean in a way the factory strap never will.
4. Black with a white line — borrow the twin's palette
Swatch built this watch twice: once in white for the full moon, once in black for the new moon. A black strap with a white line — filed under that black sibling — puts its colours under your white one, and the inversion looks deliberate rather than accidental because the two watches genuinely are a pair. It's also the strap that makes a white case look brightest, by giving it something dark to sit against. The most interesting choice here, and a neat demonstration that the collection labels are about colour, not fit.
The short version
20mm, like every MoonSwatch. White with a black line for the watch's own palette, white on white to let the sub-dial lead, plain white to keep it playful, black with white to borrow its twin's colours.
Every strap in our MoonSwatch collection is cut for this case, ships with spring bars included, and carries a lifetime warranty on rubber — with free worldwide shipping and no import costs, part of why more than 50,000 customers have trusted us with their watches. There's a full MoonSwatch strap guide covering every mission if you own more than one. Helvetus is not affiliated with Swatch AG or Omega SA.
