You're looking at a very rare Maestro FSH-1 Filter Sample/Hold pedal. These make some sounds that I haven't really heard from any other pedal. Sometimes it sounds a bit like the Mu-Tron III filter pedal, but it has a bunch of other really useful sounds as well. This is a very clean specimen. Looks to have been well cared for. All controls work perfect. Paint is still pretty intact with a few small marks. Still has the four rubber grommits on the bottom. Knobs are not original. Comes with two 9-volt batteries installed.
See video demo of similar pedal below.
From Effects Freak:
The early to mid-70s Maestro Sample/Hold may have been designed by Tom Oberheim and is one of their more interesting effects from this era. The sample/hold settings allow players to add rhythmic patterns to their playing far beyond the typical vibrato and tremolo. The filter is classic low pass and sounds incredibly smooth. Controls allow you to tweak the rate of the sample/hold as well as the frequency of the filter. This is truly a fantastic pedal.
Filter Range: Probably the width of range in which the filter moves. Could also be a fixed width with knob controlling the center frequency (high/low) of that range.
Filter/Sample/Hold: Switches the effect to envelope filter or sample/hold.
S/H Speed: Controls the speed of the sample/hold effect.
The controls consist of knobs for range (depth) and sample/hold speed. A switch that engages either the sample/hold random filter effect or an envelope follower for a unique auto wah sound.
Packing, Returns, etc: + Ship within 1 business day--pro packing. + Stand behind items with a 30-day return policy! + California residents pay 7.25% tax.