The bass version of the WR2: http://www.effectsdatabase.com/model/guyatone/micro/br2

Why should guitarists have all the fun? The BR-2 Bottom Wah Rocker features the same uniquely voiced envelope filter circuit as our legendary WR-2, but custom tuned for the low-end frequencies of the bass guitar. Now you can get the same squawky, throaty wah sounds as the WR-2 without losing the almighty bottom that holds up your band and puts people on the dance floor!

The successor of the WR2: http://www.effectsdatabase.com/model/guyatone/micro/wr3

While the unit's basic control setup remains the same (Threshold determines degree of the effect and Decay determines speed of the effect) the WR-3 features several updates to the original Wah Rocker circuit that greatly improve its functionality and performance.

The WR-2 circuit's filter sensitivity was set high to optimize it for use with "hot" pickups. However, lower output pickups had trouble triggering the filter effectively. To remedy this problem the WR-3's filter sensitivity has been improved, allowing for better note tracking and dynamic response.

Now the Wah Rocker can track even subtle picking nuances, allowing for much more creative and expressive use of the filter. This upgrade also offers improved performance for instruments with passive and/or lower output pickups, which means it will work equally well with a single coil Strat as it does with an active EMG-loaded Les Paul.

The biggest improvement to the WR3 has been the addition of a switchable Dry Blend function that mixes in clean signal against the effected signal. Since the Wah Rocker sweeps the entire frequency band when filtering, there can be some dramatic variations in volume as the signal "thins out" at the peak (hi frequencies only) and then "swamps" at the tail end of the sweep (low frequencies only). The addition of the blended Dry signal works to significantly improve the evenness of the unit's output level by eliminating volume peaks and dips caused by the filter motion.

The Mighty Micro successor: http://www.effectsdatabase.com/model/guyatone/mighty/wr

The pedal that started it all - the legendary Guyatone Wah Rocker! The WRm5 is the most recent incarnation of that time-tested classic, and offers improved control over the Wah Rocker's funky filter circuit.

In addition to the Wah Rocker's standard Threshold (effect sensitivity) and Decay (filter speed) controls, the WRm5 adds a Level control that adjusts the output level of the effect as well as a Response trimmer that controls the attack time of the filter sweep. Also included is the WR-3's uber-useful Dry Blend switch, which mixes in clean signal along with the effect.

With improved single response and additional controls, the WRm5 Wah Rocker is even funkier than before!