FK Irons One Update - Wireless Tattoo Machine, 3 Finishes, 3 & 4 mm Stroke (Made in the USA)

Cordless, coreless, easy to read.
The FK Irons One Update is the redesigned FK ONE—featuring a 1.1″ digital LCD, a brushed coreless motor, and two drop-in batteries that together provide up to 12 hours of tattooing time.
Housing made of 6061-T6 aluminum, manufactured in the USA, with voltage adjustable in fine 0.2-V increments.
You choose your finish— Stealth, Gunmetal, or Pop Pink —and the stroke length: 3 mm or 4 mm.
Built for long sessions that won’t slow you down.

At a Glance

• Brand / Model: FK Irons One Update (cordless pen machine)
• Finishes: Stealth, Gunmetal, Pop Pink (selectable as a variant)
• Stroke: 3 mm or 4 mm, fixed stroke length (selectable as a variant)
• Motor: brushed coreless motor—ultra-smooth operation
• Display: 1.1″ LCD clearly shows the settings
• Battery: two drop-in cells—short (18500A) and long (18650GA)
• Run time: short battery up to 5.5 hours, long battery up to 6.5 hours, combined up to ~12 hours
• Voltage: 5–12 V, adjustable in 0.2-V increments
• Frequency: 80–180 Hz, speed 4,800–10,800 rpm
• Grips: compatible with FK ErgoShield grips
• Material: 6061-T6 aluminum, Made in the USA

What’s new compared to the FK One

This updated version focuses precisely on the features that matter most in everyday use.
Instead of a simple LED display, you can now read your settings on a 1.1″ LCD screen.
The brushed, core-less motor runs exceptionally quietly and smoothly. Two drop-in batteries—one short and one long—noticeably extend your session time, and you can adjust the voltage in fine 0.2-V increments instead of rough jumps.
Plus, it’s compatible with ErgoShield grips.

3 mm or 4 mm stroke—which one is right for you?

The One Update is available in two versions with fixed stroke lengths.
The shorter 3-mm stroke feels gentler on the skin and really shines when it comes to shading, color gradients, and black-and-gray work.
The longer 4-mm stroke provides more impact and is suitable for bold outlines and heavy packing.
Those who primarily tattoo in one direction should choose accordingly; many artists purchase both stroke lengths for different types of work.

What this means in practice

The wide operating range—80 to 180 Hz and 4,800 to 10,800 RPM at 5 to 12 V—covers lines, shading, and filling in areas.
The 0.2-V increments give you finer control over the stroke, especially when transitioning from lining to whip shading.
The coreless motor ensures smooth, low-vibration operation, which is easy on your hand even after hours of use. And because you’re working with two batteries, you can simply swap them out when one runs low and keep tattooing instead of waiting for it to charge.

FK-One users consistently praise the series’ ease of use and versatility.
The Update version is new on the market and continues this line with the upgrades mentioned—reliable real-world experience specifically with the Update is just beginning to accumulate.

Technical Specifications (apply to all finishes and both stroke lengths)

• Finishes: Stealth, Gunmetal, Pop Pink
• Travel: 3 mm or 4 mm (fixed, as a variant)
• Material: 6061-T6 aluminum
• Display: 1.1″ LCD
• Batteries: 2 dual drop-in cells (18500A & 18650GA)
• Battery capacity: short battery 2,000 mAh, long battery 3,300 mAh
• Run time (short battery): up to 5.5 hours (depending on settings)
• Battery life (long battery): up to 6.5 hours (depending on settings)
• Maximum average runtime: up to 12 hours (depending on battery and settings)
• Voltage range: 5–12 V, in 0.2-V increments
• Frequency range: 80–180 Hz
• Motor: brushed coreless motor
• Speed range: 4,800–10,800 rpm
• Weight with long battery: 233 g
• Weight with short battery: 215 g
• Length with long battery: 136 mm
• Length with short battery: 127 mm
• Maximum width: 38 mm
• Compatible with FK ErgoShield Grip
• Made in the USA

Package Contents

• 2 drop-in batteries (short & long)
• eFest Slim K2 charger
• USB-C cable
• Travel case

Category

The One Update is the wireless all-rounder for all techniques.
If you want to adjust the stroke while the machine is running, the FK One Adjust with its wheel-adjustable stroke is the alternative.
If you’re looking for a clearly readable, smooth-running wireless machine with long battery life and precise voltage control, you’ve come to the right place.

FAQ

What colors and stroke lengths are available? Three finishes—Stealth, Gunmetal, and Pop Pink—each with a fixed stroke length of 3 mm or 4 mm. You can select either option in the variant.

3 mm or 4 mm—which should I choose? A shorter 3-mm stroke for smoother shading, gradients, and black-and-gray work; a longer 4-mm stroke for rich outlines and bold filling.

What sets the updated version apart from the original FK One? New features include the 1.1″ LCD, two drop-in batteries with longer runtime, voltage control in 0.2-V increments, the brushed coreless motor, and ErgoShield compatibility.

How long does the battery last? The short batterylasts up to 5.5 hours, the long one up to 6.5 hours; combined, up to about 12 hours—depending on the settings.

Can I adjust the stroke while the device is running? No. The One Update has a fixed stroke length (3 or 4 mm). The FK One Adjust offers an adjustable stroke.

Which grips are compatible, and where is it manufactured? Compatible with FK ErgoShield grips; housing made of 6061-T6 aluminum, manufactured in the USA.