Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16"-1/4"

For so long I went with just whatever came with the drill. These bits are so hard, and with a little bit of oil cuts super well and stays sharp. Left hand is extra handy to drill out broken/welded in screws. Love them. Would bring them to bed if I were allowed.

Bastante satisfecho con la duración, es similar a las brocas Milwaukee titanio pero a un precio menor para ser de cobalto esperaba que duraran un poco más pero aun así muy satisfecho

I bought a 10 pack because where I needed to use them, there was no store to buy replacements if it turned out these were junk. In the end, these (this) bit was as pleasant surprise. I drilled 30 holes in a steel I-beam with only needing a single bit and it still drills effectively without needing excessive force. The holes were drilled fast and easily with clean breakout on the backside. The drill bit cutting edge was does show some damage (see closeup image) after the 30 holes but it still drills effectively. I have no doubts the bit would drill another 10 holes on the same bit. I am surprised there is rust on the cutting edge since the HSS and cobalt is pretty rust resistant… I wouldn’t expect rust after sitting just a single day. The hardness of the bit must vary from the tip (very hard) to the shank end (soft) since there is a lot of damage where the bit slipped in the drill jaws a couple times (see close-up). Whatever the hardness range is, I’m happy with the combination of hardness and ductility and the overall drilling results. The bits come in a nice plastic case that can expand in length so it will hold a variety of bits including longer bits. The case opens easily to grab a replacement (I didn't need to) and closes tightly enough to not worry about spilling any. The case is right sized and not too big for the typical handful of bits needed. Overall, I'm very happy with these bits.

No era lo que esperaba muy caras y son de medida muy pequeñas, no llegan ni alos 10mm. Yo buscaba de 8mm. sta 14mm. Pero la descripción está muy confusa

Very impressive on its functionality. I purchased before Milwaukee and Dwall drills and they did not performed correctly, as a matter of fact, they got broke and it took kind of long to perform the drilling. With this MACKCPIP cobal drill bit set, i drilled like 5 holes with out any issue. Except for the smaller drill bit got broke, but the other one i used worked more then great!!!