MXR Smart Gate M-135

It's what it is, a Noise Gate. It has a lot of options such as letting you choose what kind of noise to gate (hum hiss or everything) and also offers a "high trigger range". Honestly this gate it's not bad. It's indeed smart, he senses when your signal should start to be gated and it's always smooth.
One thing i don't like though are the various switches. How can I say, I find them pretty useless. I want a gate to silence my rig, not just remove the hiss and leave some of the noise there, so this renders that switch useless. The high trigger range really degrades your tone so I always use it on normal range. If you turn the knob all the way up it will munch away some of your top end, but that's understandable and pretty common on noise gates.
I guess that for this price it's one of the best gates out there.

I run this behind three distortion pedals on one channel of my EHx Tri Parallel Mixer. This pedal tames the noise there. It could also handle noise levels coming out of the overdrive channel if I used it there. Spent a while getting everything dialed in and where it could be used most effectively. It fails to effectively gate the EHx Sovtek Deluxe Big Muff Pi Fuzz. So, after my gain stages, I'm running a tc electronic Sentry. Between the Smart Gate and the Sentry only the slightest amount of hiss gets through to the amp. I could move this Smart Gate somewhere in front of the mixer to cut down the single coil hiss of my Strat. That instrument hiss gets picked up and amplified by everything. Something to think about. And, maybe add a Sentry to each independent mixer channel.