Fosi Audio IM4 Open-Back In-Ear Monitor

Open-Back Sound. Precision Metal Craftsmanship. All-Day Comfort.

The Fosi Audio IM4 is a high-fidelity open-back in-ear monitor designed for listeners who want a spacious, detailed and balanced sound experience. Combining a 10mm N52 dual-magnet dynamic driver, dual-chamber acoustic design and precision-machined CNC aluminum housing, the IM4 delivers engaging sound with a natural sense of space.

With its lightweight ergonomic design, detachable cable and interchangeable ear tips and nozzles, the IM4 gives you the comfort and flexibility to tailor your listening experience to your preferences.

Spacious Open-Back Sound

Hear your music with greater space and air.

The IM4's open-back acoustic design helps create a wider and more natural soundstage, while acoustic damping material helps control resonance and reduce harshness.

The result is a relaxed presentation with balanced bass, mids and treble, making the IM4 suitable for music, movies, gaming and everyday listening.

10mm N52 Dual-Magnet Driver

Powerful control. Detailed sound.

At the heart of the IM4 is a 10mm N52 dual-magnet, dual-cavity dynamic driver with a PU beryllium-coated diaphragm.

The N52 magnetic system provides strong driver control, while the beryllium-coated diaphragm helps deliver crisp details, controlled dynamics and an expansive soundstage.

Precision CNC Aluminum Housing

Built from solid aluminum.

Each IM4 housing is precision-machined from 6063 CNC aluminum alloy, creating a durable and refined metal body with a distinctive minimalist appearance.

The orange metal grille adds a unique visual accent while contributing to the IM4's open-back acoustic design.

Designed for All-Day Comfort

Lightweight. Ergonomic. Skin-friendly.

The IM4's ergonomic housing is developed using extensive ear-shape data to provide a secure and comfortable fit.

Each earpiece weighs only approximately 7g, while the hollowed housing helps reduce unnecessary weight and pressure during extended listening.

The smooth aluminum finish also provides a comfortable, skin-friendly feel.

Customise Your Sound

Fine-tune the IM4 to your listening preference.

The IM4 includes three types of ear tips — Balanced, Bass and Deep Bass — allowing you to adjust the fit and sound according to your preference.

Two interchangeable sound nozzles, Brass and Aluminum, provide additional flexibility for fine-tuning the overall tonal character.

Detachable 2-Pin Cable

Flexible connectivity for everyday listening.

The IM4 uses a 0.78mm 2-pin detachable cable, allowing the cable to be replaced or upgraded when needed.

The included cable features 392 strands of 5N OFC silver-plated copper, combining flexibility with reliable signal transmission and durability.

Why Choose the Fosi Audio IM4?

• Open-back high-fidelity in-ear monitor
• 10mm N52 dual-magnet dual-cavity dynamic driver
• PU beryllium-coated diaphragm
• Spacious and natural soundstage
• Balanced bass, mids and treble tuning
• Acoustic damping material for controlled resonance
• Precision-machined 6063 CNC aluminum housing
• Distinctive orange metal grille
• Ergonomic design for all-day comfort
• Approximately 7g per earpiece
• Skin-friendly smooth metal finish
• Three interchangeable ear tip types
• Bass, Deep Bass and Balanced ear tips
• Brass and Aluminum interchangeable nozzles
• 0.78mm 2-pin detachable cable
• 5N OFC silver-plated copper cable
• 3.5mm gold-plated audio plug
• 21Ω impedance
• 109dB sensitivity
• 20Hz–20kHz frequency response

Specifications

What's in the Box

• Fosi Audio IM4 Earphones
• 3.5mm Cable
• Carrying Pouch
• User Manual
• Quick Guide
• Brass Nozzle
• Balanced Ear Tips
• Bass Ear Tips
• Deep Bass Ear Tips