The classic Dunlop Wah, unmodded.
Pedal works fine, no issues with it.
Can be powered by both 9V battery or a DC power supply with a negative centre.
Do note: if you rent this pedal it does NOT come with a battery, I wouldn't want to hand you a battery with it only for it to die right in the middle of your session/gig because the pedal has been sitting to long without use.
Product demo by Dunlop themselves: