Easy to install soap dispenser and air switch. Each hole took 5 minutes through a standard thickness hard surface (probably granite). In fact, it took me longer to build a small reservoir so I could cool myself with water while drilling (which I think helped a lot; I used "clay" for the air conditioning and built a small pond that turned into a sink drains). The center drill helped make a clean outer hole and I removed the center drill once the outer hole was started (removing the center was also necessary). Great for DIYers!