Overview

JK laser tubes are all around solid laser tubes but their specialty is beefy cutting power. They feature a mechanism on the front specifically for adjusting the internal tube mirrors to modify the alignment of photon reflection. By perfecting this alignment you can increase power output in ways impossible with other tubes. Let me be clear, this is not for the feint of heart. This process requires specialized tools to make the most of any adjustmetns you make as you need some way to measure and record power output from the tube to be sure the changes you're making are correct. That said, tubes come from the factory pre-configured and typically (though not always) offer on average higher max output power than competing brands. If your primarily going to be focused on cutting applications with laser I'd recommend checking out JK tubes as they do offer an edge. Otherwise, I would probably advise you take a look at the SPT [C-Series] or [TR-Series] tubes, or if you're feeling fancy, the [RECI W-Series] tubes.
These links take you to LightObject which is one of the best places to purchase these tubes as they keep US stock, offer fantastic support and have an A+ track record for honoring warranties. Their prices are a bit higher than you'll find other places online but dealing with them is worlds better than trying to wrestle a warranty claim out of a nameless Amazon reseller.