Vox (via the US-based Thomas Organ Company) was the first to market with a wah pedal in 1967.
The chrome-topped V847-A is based on the specifications of the original, but has modern enhancements that include a buffered input.
In use, the treadle has to travel a bit before any tonal change, and the wah occurs over a smaller percentage of the travel than we would like. The tonal change also gets a little harsh at the toe-down position.
It looks the part, does the job and it's not expensive, but if you want to get closer to that original 60s Vox experience, there's the hand-wired V846-HW at £227.