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Fosi Audio

Fosi Audio IM4 Open-Back Dynamic IEMs

Fosi Audio IM4 Open-Back Dynamic IEMs

  • Authorized Retailer
  • Free US Shipping $49+
  • 1-Year Warranty
  • 45-Day Returns
$98.99 USD
$98.99 USD
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The Fosi Audio IM4 is a wired in-ear monitor using dynamic drivers in an open-back design - an unusual combination in a category dominated by sealed shells.

Open-back IEMs trade isolation for a more relaxed, less pressurized presentation, so these make more sense for home and desk listening than for a noisy commute. Run them from a dongle or desktop amp you already have, and treat them as a change of pace from your sealed daily drivers rather than a replacement for them.

  • Dynamic driver in-ear monitors
  • Open-back shell design
  • Wired connection

Authorized Fosi Audio retailer. Free US shipping over $49 and 45-day returns.

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Good to know

Frequently asked questions

Is this unit genuine?

Yes. TonePier is an authorized retailer — every unit comes from the brand or its official distributor, carries a valid serial number and is covered by the full manufacturer warranty.

How long does shipping take?

SKUs stocked in our US warehouse ship within 1–2 business days. Items shipped direct from our China hub typically arrive in 8–15 days with full tracking. The product page tells you which applies before you order.

What if it isn't for me?

You get 45 days to decide. Keep the packaging, keep it in like-new condition, and send it back for a refund. Ear tips unsealed for hygiene reasons are fine — we expect you to actually listen.