"used this and a 54mm one ate through 3" joists no problem, self feed, just be careful to put your drill on slow speed and watch your wrists. this with a Makita perfect combo. only down side the threaded tip came loose on one so had to push more."
"This drill bit may be pricey but it does save a lot of time and effort. We were using these all day to drill joists for pipework and boy did it eat the timber. Only gave it 3 stars for features as lets face it how many features does a drill bit have. Only negative is that you do need a 13mm chuck on the drill so some angle drills may not be man enough for the bit. would definitely recommend though"
"After struggling with the usual flat bits, I thought I would try this - Drilling through joists for cables was so, so , SO much faster! - took me a few minutes with the flat bits, this one took about 10-15 seconds!!! leaving a neater hole too!"