I purchased this sight glass for my Berkey water filter so I could have a stainless steel spigot with a sight glass (seems they just started selling one but this one is cheaper AND more fun!). After some effort it's working great. This assembly includes the bulkhead fitting to cross from inside the tank to outside and unfortunately that fitting only includes one silicone gasket. One gasket is not enough to seal a tube from inside a tank to the outside unless the inside flange and the tube through the sidewall are a single unit and the threaded nut that provides clamping force against the sidewall is on the *outside* of the tank. This assembly is the reverse: the outside flange is a single unit with the tube and the clamping nut is on the inside. No amount of tightening will give a reliable seal here* it'll just ruin the soft silicone gasket. To reliably seal this assembly gaskets are necessary both inside and outside the sidewall. Well I swung by my hardware store and picked through their bins for a while and found two gaskets that would fit (the silicone one was a loss) and now it's working great. * For those who care this is because the thread used to clamp to the sidewall is a machine thread with a nut. It is not a plumbing thread which cannot be used with a nut and cannot be used to provide clamping force. This all makes good sense but the effect is that the thread does not seal perfectly: water creeps along the thread between the nut and the tube happily flows right through the center hole of the gasket through the sidewall and right out onto the countertop. Adding a second gasket on the outside resolves the issue as the water that makes it through the sidewall is trapped against the outside flange: there is no further thread to sneak along and the outer gasket seals the escapes along the tank sidewall or along the flange.

Installed this on a Grainfather sparge water heater. After doing the standard installation, it simply would not stop leaking. I then purchased from a on-line vendor thicker (1/4") silicon gaskets and replaced the original one and added an additional gasket on the outside of the kettle. There is also room for a washer for the outside gasket but I did not use one. As mentioned in the other review, the sight glass leaked where it screws into the bulkhead. This was fixed with Teflon tape and joint compound (use both, tape alone was not sufficient). So, good product but tricky to install.

I purchased this sight glass for my Berkey water filter, so I could have a stainless steel spigot with a sight glass (seems they just started selling one, but this one is cheaper AND more fun!). After some effort, it's working great.This assembly includes the bulkhead fitting to cross from inside the tank to outside, and unfortunately, that fitting only includes one silicone gasket. One gasket is not enough to seal a tube from inside a tank to the outside unless the inside flange and the tube through the sidewall are a single unit, and the threaded nut that provides clamping force against the sidewall is on the *outside* of the tank.This assembly is the reverse: the outside flange is a single unit with the tube, and the clamping nut is on the inside. No amount of tightening will give a reliable seal here*, it'll just ruin the soft silicone gasket. To reliably seal this assembly, gaskets are necessary both inside and outside the sidewall.Well, I swung by my hardware store and picked through their bins for a while and found two gaskets that would fit (the silicone one was a loss), and now it's working great.* For those who care, this is because the thread used to clamp to the sidewall is a machine thread, with a nut. It is not a plumbing thread, which cannot be used with a nut and cannot be used to provide clamping force. This all makes good sense, but the effect is that the thread does not seal perfectly: water creeps along the thread between the nut and the tube, happily flows right through the center hole of the gasket, through the sidewall, and right out onto the countertop.Adding a second gasket on the outside resolves the issue, as the water that makes it through the sidewall is trapped against the outside flange: there is no further thread to sneak along, and the outer gasket seals the escapes along the tank sidewall or along the flange.

This thing has worked beautifully in my kettle. Obviously, it works - it's a glass tube, that's kind of a given. But the construction is solid, I've never had any sort of leak issues, and there's a huge hidden perk - the stopper is 1/2" NPT, so you can toss in a PTD sensor or even just a thermowell if you'd like boil/HLT control. Pretty neat!Definitely worth the money, it's exactly what you think it is