This was overall an ok product if you can avoid the negatives I will describe here. The drill bit was fine. Drilling was no problem. Getting the hole in the right place was challenging because unless you have done this before, you dont really know how far up the water is going to be on the box in the tank. I thought I knew about where it would be, but found I was off about 3/8". Water level was that much higher than I thought it would be. There is not really any way to adjust the level down if you have it too high and I actually drilled with the resulting water level a bit too far up for my comfort. Read some previous people's experiences on some forums and you should do ok. Most seem to be drilling too far down - this is probably better than drilling too far up as I did. You still may need a longer pvc than the red one they include to make the overflow completely quiet. They should include a 1" strainer for the lower exit out of the outer box just to be sure your pipe remains free of anything that might get in to clog it up. Not sure if it's really necessary but I would recommend it. The next thing is the instructions are poor and don't tell you where the gaskets really need to go. So after having multiple leaks the first time getting water in it, I ended up over tightening one of the nuts, thinking I just did not have it tight enough, and the nut snapped. Then I had to replumb the box so I could get a new nut on. Luckily I had one around from another overflow. Poor instructions were at fault here. If I used this product again, knowing what I know now I would not have these issues, but buyers should be aware this is a nice product if you are an experienced tank driller and plumber, and if not you might want to try to find some help. Some simple better instructions and troubleshooting tips would be priceless because it seems almost everyone has the same issues and solutions. After getting it going and working nice, I would say, most definitely do this rather than a tube over the top overflow. If you can drill, do it. I tried that and it was a huge pain over all trying to tweak the flow to avoid bubbles in the tube, and even then you always worry about losing siphon during a power outage. The last thing is I would absolutely recommend also drilling for returns. I am using a pipe over the top for the return and while perfectly functional and trouble free, it is a bit of an eyesore, and if I could do it again I would do through the glass returns. Hope this helps everyone thinking about this for your next or new tank. Wanted to give it 3 stars because instructions are criminally negligent, but overall it is a nice product only marred by instructions that you can just choose not to look at if you can get help from elsewhere. Will give it 4 for that reason.Drilling the tank with the accompanying drill bit is easy, but the template is likely for a rimless tank. To set the water level on a rimmed tank, you need to set the weir against the rim and mark the location of drilling. The template can be used as guide together with a clamp to hold it in place. Secondly, Eshopps indicates that the gaskets should be lubricated, but no lubricant is provided. Thirdly, I would have preferred that the bulkheads were threaded rather than slip fittings and alternative source bulkheads for 1-in plumbing is too large. Lastly, to have a warranty, Eshopps requires registration of the product within 14 days of purchase and it seems that this must be done by mail.The overflow itself is solid, nice and sleek looking on any tank. Also extremely quiet when tuned with a valve on the main intake. Has the back up standpipe as an emergency which is also nice in case of a sudden stop in the first pipe. Overall the product is a great idea and design especially for a typical or standard tank that you may want to convert to a reef tank. I installed mine on a 55 gallon and it went very smoothly with the included hole saw. Be sure to have the drill on high speed and let the weight of the drill do the work when drilling out the glass, also be sure to spray it and keep the drill bit wet when drilling. You can easily build a small temp reservoir to hold the water in place with duct tape instead of plumber’s putty. I will say, the instructions are pretty useless. It’s written out like I text messaged someone to quickly learn how to do something in 5 minutes. As someone who is in the trade field I didn’t need the instructions to do it but it may definitely be harder for someone who doesn’t do this kinda stuff all the time. Best bet is to look it up on YouTube if you need to learn about it a bit. DO NOT USE THE TEMPLATE THAT COMES WITH IT AS A HOLE MARK. If you put the template right against the plastic trim of the tank you will not have a high enough water level in the tank. Use a sharpie to mark out where the bulkhead will be from the inside once you have the internal overflow box up against the top of the trim. It’s the only way your water level will be high enough. Once you’ve marked it THEN use the template as merely a drill guide, but not to mark where your hole should be. Once all of that is over with the overflow is nice however mine came with a bad gasket and I had to get a new one because I had a tiny leak upon start up. Not sure if mine was just defective or they just come with cheap gaskets, but no matter how much I tightened it with channel locks it would not stop so I had to replace the gasket on the external side.you will need a ball valve FOR SURE on your main intake. Otherwise it may be too powerful or too noisy. I recommend putting a piece of highly porous filter pad over the main intake bulkhead inside the overflow box, really dims the noise out to nothing and avoids a whirlpool siphon. Overall it’s a nice overflow but not as simple as portrayed.... be very careful the way you play your cards when installing it like I said above. Other than all that, when it’s done definitely headache free and reliable. I would recommend it hopefully just mine came with a bad gasket.Real nice overflow but the gaskets that come with the kit are terribleVery nice overflow. Fits well for what I needed on my Zoomed 50 gal Lowboy. Only 2 issues.1. The instructions say gasket placement between the interior black box and the glass (good) and then inside the outer box underneath the bulkhead nut (bad). The bulkhead nut one needed to be moved to between the glass and the outer clear box. There was a definite leak in the threads that would drip on the outer glass. After I moved that gasket, no more leak. It took some scouring on R2R to find this info. Save yourself headache and just start that way.2. The water draining sound was louder than expected. Not that big of a deal just worth noting.Other than that, would recommend.Have fun trying to get this sealed. You will need to really water test this unit and other reviews don’t lie either. Pretty cheap construction. I would never buy eshopps junk againI was looking forward to receiving this overflow as the other Eshopps equipment I had seen in person was of a high quality. This one wasn't!Ordered this in Australia but believe that the overflow was sent from the USA Amazon? Unfortunately if I was guessing this may have been returned to Amazon from someone else. The acrylic had some slight scuffing, the Eschopps logo on the clear part has a scratch through it, some of the joining of acrylic has bubbles in it and a small chip in the black plastic part of the overflow.Wont be installing on my tank. Thinking of other options such as a reef Synergy overflow.Great product fast delivery!worked great!