Milwaukee’s M18 TOP-OFF just stopped being a pocket accessory. The new 350W Power Supply & Charger (2856-20) is confirmed at $269 and set to ship in February 2027. It was teased at Milwaukee’s Pipeline 2026 event earlier this month with no price attached. Ohio Power Tool confirmed the full spec sheet and $269 MSRP this week.
2856-20 at a glance
- Model: 2856-20
- Output: 350W pure sine wave inverter
- Ports: 2 x 120V AC, 1 x 100W USB-C PD, 1 x 15W USB-C
- Battery: one M18 pack to run, second for up to 2X runtime
- Hot-swap: swap a dead pack without interrupting power
- Display: real-time load and pack level
- Charging: doubles as M18 charger via 100W USB-C
- Stacking: locks into PACKOUT, built-in handle
- Price: $269
- Availability: February 2027
That 350W is the first big jump in the TOP-OFF line. Older models were fine for topping off a phone or a drill battery on the tool box. This one runs real AC gear. The pure sine wave output matters here, because cheap inverters dump modified square wave at sensitive electronics. Milwaukee went with a cleaner sine wave for laptops, camera gear, and anything with a switching power supply.
Two AC outlets also changes the math. You can run a speaker and charge a laptop at the same time, or keep a monitor and a drill on charge. The four-port total (two AC, two USB-C) is what pushes it out of accessory territory and into a genuine portable power setup.
The hot-swap dual battery
Dual-battery hot-swap is the feature that sets it apart. A readable display shows which pack is doing the work, so you can pull a dead battery and drop in a fresh one without the laptop losing power. Nobody wants the inverter to hiccup mid-save.
It also collapses the inverter-plus-charger combo into one unit. A 100W bidirectional USB-C port tops off M18 batteries while you are drawing power. For anyone already on the M18 platform, that means one PACKOUT-shaped box handles both roles instead of carrying a separate charger and power source.
How it fits the lineup
This sits a step below Milwaukee’s big Roll-On units but far above the mini TOP-OFFs. If $269 and a February window feel like a long wait, the Roll-On lineup covers the same ground at a much higher price point. Against 300W-class power banks it wins on the M18 angle: you already own the packs, and it both powers and charges from them.
Pricing lands between the old compact TOP-OFF and the heavy Roll-On gear, and the competition has nothing that hot-swaps a dead pack mid-flow in this size class. That cleaner-sine spec is the differentiator worth checking if you run sensitive electronics on a jobsite.
Who should care
This is not a weekend-garage buy for most homeowners. It is aimed at pros who need real 120V output away from an outlet, plus the crew that already lives on M18 batteries and wants to stop buying fuel for a generator. Camping and tailgate power are the leisure edge of the same capability.
What we don’t know yet
Runtime figures for specific batteries are not published, so treat any hour count as a guess until Milwaukee posts a spec table. Same story on the exact charging current to the packs. Check manufacturer specs before you rely on this as a full jobsite power source.
One open question is how the 100W bidirectional port charges older packs. The 350W is certified to a load rating, not a charging-current spec across every M18 battery variant, worth confirming if you intend to charge mixed packs here.
When and where it ships
Milwaukee lists a February 2027 ship window at $269. No retailer has a listing yet, so there is no affiliate link to share today.
Bottom line
Milwaukee’s M18 TOP-OFF 350W (2856-20) at $269 is the first TOP-OFF that behaves like a real power supply instead of an accessory. The hot-swap dual battery, pure sine wave output, and built-in charging make it the cheapest on-ramp to portable AC power if you already own M18 packs. February 2027 is a long lead, so set your expectations accordingly.
Related reading: our best portable power stations for job sites roundup, the Milwaukee ROLL-ON 3301R launch, and the full Milwaukee Pipeline 2026 roundup for everything else that debuted at the event.