We have a MINT condition Beyerdynamic T1 Tesla headphone for sale.  This was our demo, an comes with original box, and manual.

The completely redesigned transducers achieve values of over one Tesla (a unit of measurement for magnetic flux density). That provides the listener with almost double as much volume as traditional headphones. The increased efficiency also leaves the T1 with greater power reserves for dynamic, undistorted sound and nearly lossless conversion of electric signals into sound waves. The extremely lightweight 600 Ohm voice coil provides transparency and perfect impulse fidelity.The elegant look of the T1 compliments the technical achievements, with even the smallest of details selected by hand. This model reaffirms beyerdynamic's commitment to world-class "Made in Germany" quality.

Open Back Design 600 Ohm, 5 - 55,000 Hz

MSRP = $1400 USD = $1725 CAD