SUNLU S2 or PolyDryer: do you need a filament dryer yet?

Short answer: if your rolls are new or stored sealed with desiccant and printing normally, you probably do not need a dryer yet. If a roll is already moist, or its maker tells you to dry it, the two packages answer different needs. SUNLU S2 ($44.99) is a heated chamber you can feed from while printing. PolyDryer ($79.99) is a drying dock plus a sealable box, with additional boxes available for storing more rolls.

Method: Exact US package prices, stock flags and shipping policies checked October 3, 2026 at 08:10 UTC. Manuals, specification graphics and the manufacturer-linked report were checked October 2. We have not used either dryer or measured drying performance, temperature, noise, power draw or print results. This guide does not choose a safety or drying-performance winner. Prices are item prices before tax; manufacturer links are ordinary, nonaffiliate links.

Do you need active drying at all?

A sealed container and a dryer do different jobs. Our storage guide explains the difference: a sealed box with desiccant slows moisture absorption. It does not dry a roll that is already wet.

Start without a dryer when:

• your rolls are new or were closed in a sealed bag or box with desiccant after use,
• you print common materials such as the beginner PLA or PETG choices and they print normally, and
• you have somewhere sealable to keep an opened roll.

Consider active drying when the filament maker’s instructions call for it, or a roll was left open and now prints poorly. Poor surface finish or stringing is a reason to investigate. It does not prove the roll is wet.

If you need sealed storage, compare the cost of a container you already have with either package below.

The two exact packages we checked

Both selections are US-plug packages from the manufacturer’s US store. Item prices exclude tax and filament. Shipping is summarized from each written policy, not from a checkout quote.

Power ratings are documented limits, not measured energy use. Both makers list materials beyond PLA and PETG. That list is their compatibility claim, not our drying result.

Which setup suits your rolls?

Check spool size first. Measure your reel’s outside diameter and width. PolyDryer documents a 205 × 78 mm envelope. SUNLU’s current store specification graphic lists 210 mm diameter × 85 mm height for the S2. These are manufacturer limits, not measurements we made. Confirm that the S2 limit applies to the delivered Black US revision before buying it for wide, 2 kg or unusual reels. Neither maker’s listing proves fit for your particular reel.

Check the reel’s heat tolerance. Cardboard and plastic reels have their own limits. Check the filament maker’s drying temperature and time against the device manual and the reel’s heat tolerance. Stop if the instructions do not establish a suitable procedure for your combination. Each manual has its own material table; we do not turn either into a universal recipe.

Choose by the job:

• Dry a roll while it feeds the printer, one roll at a time. The S2 is documented for this. You still need a separate sealed container for storage between uses.
• Store several opened rolls sealed and dry each as needed. The manual’s setup mounts one PolyDryer box on the dock. Keeping each roll in its own PolyDryer box adds $29.99 per extra box; drying rolls in turn and returning them to suitable sealed storage does not require a box for every roll.

Follow the device manual for unattended use. Polymaker markets continuous drying during storage. Its manual also says not to leave the dryer unattended in Continuous Mode, and to turn the power off when unattended. Use only the supplied adapter for either device.

What a complete setup costs

Setup	Observed item cost	Add to your own total
S2 for one roll	$44.99	Sealed container and desiccant, unless you already own suitable storage; tax
PolyDryer for one roll	$79.99	Tax; a replacement hygrometer battery later
PolyDryer for three stored rolls	$79.99 + 2 × $29.99 = $139.97	Tax; a lone box order under $35 adds $5.99 by Polymaker’s written policy

Neither package includes filament. A dryer is not part of the starter-cost examples. Add only equipment you need to your budget planner amounts. If you are still choosing rolls, a single spool’s delivered cost and a package your printer can feed come first.

What remains unknown

We have not established:

• how well, quickly or evenly either device dries any roll,
• noise, real power use, durability or comparative safety,
• physical reel fit or whether the S2 seals for storage,
• which S2 display your unit has. SUNLU’s pages describe different screens, and one describes a humidity readout, so check the delivered unit and its manual.

The S2 report concerns a tested sample under a European standard. Its adapter line lists 100–240 V input and 24 V 48 W output, but the next appliance-rating line names S1 PLUS even though the report identifies S2. It does not establish what ships with the US-plug variant. The current official leaflet’s “Detailed Manual” QR leads to a page that returned 404 when checked October 2. Prices and availability change. Recheck the exact selection, shipping to your address and current manuals before ordering.

Before buying the S2, ask the seller to document these details for SKU DLZ-US-SL-S2FD-US, variant 48817677402394:

• Do the advertised maximum supported spool diameter and width of 210 × 85 mm apply to this delivered revision? Compare them with your measured reel, including any protruding edges.
• Which display ships with this Black US package, and does this revision include a humidity sensor/readout? The conflicting screen descriptions do not settle this.
• Which original adapter model ships with it? Request its label showing input voltage/frequency and output voltage/current, plus the current instructions for this exact package.

The US-plug option confirms the selected plug option; it does not document the supplied adapter’s input rating. If the seller cannot supply the fit and adapter documentation you need, this guide cannot establish that the S2 suits your reel or electrical supply. A different regional package or a sample certificate does not establish those details.

Sources

1. SUNLU FilaDryer S2: Shipment USA | US Plug / S2(Black) *1 Set — last checked: 2026-10-03 (DLZ-US-SL-S2FD-US; $44.99 USD, storefront available flag true on October 3 at 08:10 UTC. Filament bundles excluded.)
2. SUNLU FilaDryer S2 user guide (packing list, warranty) — last checked: 2026-10-02
3. SUNLU S2 official store specification graphic (nominal spool envelope) — last checked: 2026-10-02 (Current S2 product gallery lists maximum capacity φ210 × 85(H) mm. Manufacturer specification, not a measured fit result or delivered-US-revision confirmation.)
4. SUNLU FilaDryer S2 specifications (SUNLU main site) — last checked: 2026-10-02 (48 W, 70°C maximum. Display/humidity description conflicts with the US store page.)
5. FilaDryer S2 CE-LVD test report CTB26052503404S01 (adapter rating) — last checked: 2026-10-02 (Third-party lab report commissioned by SUNLU for a tested sample under an EU standard; not a US-variant or safety-comparison finding.)
6. SUNLU shipping information — last checked: 2026-10-03
7. Polymaker PolyDryer: Dryer Dock + Storage Box, US Plug — last checked: 2026-10-03 (PX01002_A; $79.99 USD, available flag true on October 3 at 08:10 UTC. Additional Box only PX01003: $29.99, available.)
8. PolyDryer and PolyDryer Box user manual — last checked: 2026-10-02
9. Polymaker shipping policy — last checked: 2026-10-03

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