The photos below show MB-1 being used with five different couplers:

MeterBuilder MB-HF1 Coupler (included with MB-1 Kit)

PowerMaster HF-3K Coupler

Palstar PM2000AM Coupler

WaveNode HF-1 Coupler

WaveNode LP-1 Coupler (rated at 50 watts max)

You can calibrate your own couplers with MB-1 to achieve measurement accuracy to
 within 1% of your Measurement Reference.

The photos below show MB-1 measurements after being calibrated against a measurement reference. The measurement reference is left in the line for comparison.

Using MB-1's 60 point calibration feature, MB-1 can be calibrated to within 2% (typical better than 1%) of an arbitrary reference for power levels above 1 watt as shown below. Accurate calibration can also be achieved down to 10 milliwatts if the reference supports low power measurements.  In the examples below, calibration was performed on 9 of the 60 available calibration points.

For convenience, the measurement reference used below is an Alpha 4510 since it eliminates the complexity of switching in calibrated attenuators for this demonstration. However, any accurate reference can be used.

In all of the pictures below, the top left 7-Segment LED module is displaying Forward Power.
(MB-1 Kits have a darker bezel than the ones shown in the pictures below, and also have a polished bevel edge.)

Since you can't believe everything you see on the Internet, your skepticism of the A/B comparisons shown below is understandable. If you are at the Dayton Hamvention for the 2011 Season, drop by booth 529 to see a live demo.