Confidential calls at your own desk should stay off other people's phones. This compact unit fills the space around you with ultrasonic interference, so phones and voice recorders nearby capture distortion instead of clear speech.

• Covers a small room: the interference reaches 1–6 m (up to 18 ft) from the unit.
• Silent in use: the ultrasonic field runs silently, so your conversation carries on as normal.
• 2–4 hours per charge: an 8000 mAh rechargeable battery, back to full in 3 hours.
• Fits on a desk: 16 × 8 × 9.3 cm, small enough for a desk, cubicle or meeting table.

Good to know: it works on microphones, so a camera still records pictures; only the sound it captures is distorted.