The WBS RealStop© is a real double-stop and has nothing in common with the usually built-in so-called Feelstop which most manufacturers use.
Historically, a feel or double-stop is used on steel guitars to be able to address more than one note with a knee-pedal. The best example of this is the second string on the E9 neck; Here, a kneelever is typically used to detune the Eb to D and on to C #. With a Feel-Stop - as it is installed in most guitars - this intermediate stop for the D is to be noted only by a slight resistance with the result that the sound is usually inaccurate.
By contrast, the WBS RealStop©, which is manufactured in a separate housing, allows you to hit this intermediate tone accurately when using the kneelever. No more looking for the stopover and no spongy tuning. An elaborate but perfect solution. The pictures on the right shows the WBS RealStop©.