VEVOR Diamond Core Drilling Machine, 4in Handheld Wet Concrete Core Drill Rig, 1100-2400RPM Two Speed & 1-1/4″ Thread & 2 Bubble Levels, 3-4in Drilling Diameter for Concrete Brick Block Stone, 1500W

I purchased this because it was about the same price as a rental without all the hassle and then I would have the tool if I ever need to drill another hole. And it worked. Very well. But a few things you should watch out for if you are new to this work. First, a 4″ dryer vent needs a 4.25 inch hole. Not a 4″ hole. I suspect this is the perfect size for a metric country with metric ducts, but if you are looking to install a 4″ dryer, the hole will be really tight and it will be hard to insert the exhaust cover let alone get the duct through the hole. The seller was absolutely clear on the hole size, but the customer (me) did not appreciate its significance and it is really hard to make a hole larger!The second issue is that the spring on the trigger is pretty strong. My foundation was 12.5 inches of poured concrete. It took quite some time to drill the hole (with breaks) and by the end my hand was cramping. Clearly more time in the gym and less writing Amazon review would probably help. One solution might be to have a lock, but with the potential for the bit to bind, this could be quite dangerous. I think a softer spring would be best solution.This brings me to the next concern. There does not appear to be a clutch on the drill. Twice the bit bound in the hole and it is quite powerful. My hole was 6 inches above ground so this was not a risk, but if I was on a ladder, it could have been quite scary. So definitely don’t get the bit out of angle or you will quickly find the drill twisting out of your hand.Starting the hole can be tricky because the bit is water cooled and does not have a pilot drill to hold it in the center. To address this, I cut a 4″ hole in a piece of scrap wood and rested the drill in the hole until it started to cut into the wall. This avoided the drill from wandering as it spun and before it started to cut. This take a bit longer but is worth the time!Speaking of water cooled, as some of the comments mention, the drill comes with a fitting that probably works great in China, but for which no US garden hose can attach to. I don’t event know what it is. It looks a lot like the quick connects they have at HomeDepot, but it is a different size and does not stay connected. The fitting the male connector screws into is not tapered and is metric. So unless you have access to metric plumbing parts, you will need a 1/4 inch brass fitting and rely on it to cross thread (which it will with enough tape) and then a bushing and finally a garden hose connector to allow you to connect a US garden hose to the drill. The fitting is stainless steel so brass will deform nicely and work. Don’t use steel! This is a simple trip to Lowes or HomeDepot, but will set you back another $30.Last point is that this drill is heavy. If you are young and fit this may not be an issue. But it takes time to drill through any strong foundation and you will have to hold this drill quite steady for a long period of time or it could bind. So take lots of breaks, see if someone can spot you for a time or two so you don’t make a mistake.I don’t regret the drill, but do wish the 4 inch bit was a quarter inch larger. Given the hassle with getting the duct through the hole and converting it to work with our garden hoses, I would probably rent one next time since I only needed the one hole. But if you can work with a 4 inch hole or are using the smaller bits for irrigation hoses or wires (and they work with that diameter) and you will want to work over several days (like most DIYers), this is definitely worth getting because renting over multiple days is quite expensive.Hope this helps.