This is the best spring reverb pedal I've encountered. Using the Source Audio 'Neuro Editing System' through your phone gives this pedal hidden depths.
Here is a brief description of the True Spring by Source Audio but I highly recommend going to their website to find out more and get a full specification.
'Turn on to the vintage charm of natural spring reverb coupled with pulsing tremolo. Source Audio doesn’t depend on the off-the-shelf reverb effects processors found in many modern reverb pedals, we meticulously craft every one of our proprietary effects engines and load them to high-powered, 56-bit Sigma DSP. Our two man engineering team of Bob Chidlaw and Jesse Remignanti put years of collective man-hours into capturing every nuance and idiosyncrasy of the spring reverb and tremolo effects from some of the music gear industry’s most iconic guitar amps and outboard gear. The result is indisputable sound quality with magnificent tonal depth and precision.'