Top positive review
Does the job
on 26 July 2017
I was having trouble trying to drill into the Italian dual purpose tiles in my bathroom so I bought these Silverline bits. Following recommended procedure I.e. Slow speed, no hammer, tip lubricated with 3 in 1 oil and drilling in 5 second bursts with re-oiling in between the hole went through in a minute with a perfect finish. I only need to drill four holes so I can't comment on their longevity but I notice Silverline offer a lifetime guarantee.
Additional: I notice that lubrication with water is also mentioned by others.