Which FK Irons Machine Is Right for You?

Quick answer:

Want one machine that adjusts on the fly? One Adjust. Adaptive tech for colour and shading? Flux Max. A simple, long-lasting wireless workhorse? Spektra Flux. Need to switch between wired and wireless? Exo.

Four machines, four different jobs, and no shortage of conflicting opinions on which one's "best." The better question is which one matches how you actually tattoo. Here's what each is built for.

FK One Adjust: the all-in-one

The One Adjust changes stroke length while the machine is running, from 2.0mm to 5.0mm in 0.5mm increments, without powering down. That's the whole pitch: one body instead of three or four.

Best for: artists who want a single, versatile machine for lining, shading, and packing without swapping bodies mid-session.

Each of its two drop-in batteries runs about 6 hours, so you get 12+ hours combined runtime between swaps.

Flux Max: the tech powerhouse

The Flux Max is built around adaptive technology that reads how you're working (needle resistance, pressure, voltage) and adjusts in real time. It comes in three stroke options: 3.2mm, 4.0mm, and 4.5mm, so you can tune it to your style before you even touch the settings.

Best for: artists doing complex colour work and shading who want the machine adapting with them, not just running at a fixed setting.

Battery life runs roughly 6 to 10 hours per PowerBolt depending on your settings, with a digital display for voltage, hertz, and battery status built into the machine itself.

Spektra Flux: the wireless workhorse

The Spektra Flux was FK Irons' first truly wireless machine, and it's stayed simple on purpose. 4.0mm direct drive stroke, Bluetooth-enabled, and up to 10 hours of battery life on a single charge, recharging in as little as 2 hours via USB-C.

Best for: artists who want proven, no-fuss performance and extended session time without thinking about battery swaps.

If you've been coil or rotary your whole career and you're wireless-curious for the first time, this is usually the easiest place to start.

Exo: wireless and wired, your call

Exo runs the same motor as the Flux line, but it's modular. Swap the RCA module in for traditional cable power, or swap the PowerBolt battery pack in for wireless, on the same machine. It's also available in three stroke options (2.5mm, 3.2mm, or 4.0mm direct drive), giving you more range to dial in than the comparison below shows at a glance.

Best for: artists who need to move between wired and wireless setups depending on the job, the studio, or the day, without owning two separate machines.

Wireless runtime on the PowerBolt is up to 10 hours, matching the Spektra Flux.

Quick comparison

Machine	Stroke	Battery	Connectivity	Weight	Workflow fit
FK One Adjust	2.0–5.0mm (adjustable)	~6 hrs per battery (12+ hrs combined)	Wireless	244–268g (battery dependent)	All-in-one: lining, shading, and packing without swapping bodies
Flux Max	3.2mm / 4.0mm / 4.5mm	6–10 hrs (settings-dependent)	Wireless	206g	Colour work and shading, adapts to you in real time
Spektra Flux	4.0mm	Up to 10 hrs	Wireless	178g	Lining and packing, simple and proven
Exo	2.5mm / 3.2mm / 4.0mm	Up to 10 hrs	Wireless + Wired	189g	Switching between wired and wireless setups

BEST FOR LINING

If clean, consistent linework is your priority, Spektra Flux is the straightforward choice. Its fixed 4.0mm direct drive stroke is purpose-built for line consistency, and the simple three-button interface means less fiddling mid-session.

Exo at 4.0mm is the alternative if you also want the option to go wired on the same body.

BEST FOR COLOUR PACKING AND SHADING

Flux Max is the pick here. Adaptive technology reads your pressure and needle resistance in real time, and the three stroke options (3.2mm, 4.0mm, 4.5mm) give you room to dial in shading and colour work without switching machines.

BEST FOR ALL-DAY SESSSION

Spektra Flux and Exo both run up to 10 hours on a single charge with the most consistent battery life in the lineup, since Flux Max's range (6–10 hrs) shifts depending on your settings. If you'd rather swap a battery than wait out a recharge, One Adjust gets you 12+ hours combined across its two drop-in batteries.

BEST FOR WIRED-OR-WIRELESS FLEXIBILITY

Exo is the only machine in this lineup built to do both. Swap the RCA module in for a traditional power supply, or swap in the PowerBolt for wireless, without owning two separate machines.

From the BSTS shelf

All four machines ship same-day on weekday orders placed before 2PM from our North Geelong warehouse. Explore the full FK Irons lineup, or jump straight to a specific model:

FAQ

What's the real difference between Flux Max and Spektra Flux?

Flux Max reads your working style and adjusts in real time, with three stroke options to start from. Spektra Flux runs a fixed 4.0mm direct drive with longer battery life and a simpler interface. Flux Max is the more adaptive machine, Spektra Flux is the more straightforward one.

Can I actually use the Exo both wired and wireless?

Yes. Swap the RCA module in for a traditional power supply and cable or swap in the PowerBolt battery pack to go cordless. Same machine, same motor, either way.

How long does One Adjust battery actually last?

Each of the two included batteries runs about 6 hours. Since you swap between them rather than running one flat, you get roughly 12+ hours of combined runtime across a session or a full day.

Which one should I get if I've never gone wireless before?

Spektra Flux is usually the easiest entry point. Fixed stroke, simple three-button interface, and the longest proven battery life in the lineup, so there's less to think about while you get used to working cordless.