Ox Trade XL 3 Dry Core Drill Bit & Accessories Case (XL3). This set of 3 diamond tipped dry core drill bits can be used to cut holes into most common building materials including clay, brick and concrete. The set consists of 38mm, 52mm & 117mm dry core drill bits in an aluminium case with numerous useful accessories. The dry core bits have turbo segments which help to increase the cutting speed through common building materials. The drill bits have been shaped with a spiral design to help clear away dust from cutting which not only prolongs the life of the bit but also helps with faster cutting.