5 out of 5 were usable. I use a lot of these, so I know that's well above average in the DOA department. Packing is typical with several layers of bubble wrap and a soft envelope, got no bent pins this time. Each driver had its own anti-static bag, that's a plus.
if you're new to these, be sure to turn the current-set pot all the way clockwise. Typically these come set to mid range, which is equivalent to about 2 or more amp which will lead to a thermal shut down in a few seconds.
You can consult the 'tube to find out how to set power levels the tech way.
Or if you are without a meter or just pragmatic, you can power up with a motor attached and some simple Arduino program delivering pulses. At first the motor won't move because you've set the current to 0 amps. Turn the pot counter clockwise SLOWLY. At some point (and it won't take much turning!) the motor will start to run. Pinch the shaft hard with your fingers and continue increasing the current until you just barely can't stall the motor. At that point you are likely to be at, or slightly below, the proper current rating for a middle sized NEMA 17 motor. Touch your fingertip to the NEG power connector to discharge any static. Gently touch your finger to the top of the chip...it should feel a little warm, but not hot! If it's hot, reduce the current until you find some sweet spot balancing heat and motor performance.
Best practice calls for using a heat sink, the ones that come with this kit are (typical of all kits on Amazon) kinda small, but better than nothing. The kit ones will let you set current about 0.1 amp higher than without. If you're really ambitious, but some tall heatsinks, sand of the anodize off the contact surface of the sinks to expose bare aluminum, and glue the sink to the chip with Arctic Alumina Thermal Adhesive, which is actually a two-part epoxy. It sets fully in about 15 minutes. That will let these drivers max out close to 1.9 or 2.0 amps without thermal shutdown, which is very impressive. And it will prevent the heatsink from shifting position which can happen with the spongy, peel off adhesive pads that come with the sinks. It just takes a tiny dab, grain of rice size or even smaller. A tiny dab will do ya, gramps. That stuff works really good, and although expensive one kit will do a LOT of heatsinks, so call all your friends for an upgrade party... wear masks please.
PS, sometimes when adjusting current the driver will do a thermal shutdown. Don't despair, and don't toss it. Turn everything off, give it a 5 minute rest, and it's good as new.
PS, it is not entirely an old-wives tail that powering up these drivers without a motor attached will kill them. Be safe and don't tempt fate. And be darned sure you've got these things plugged in with the right orientation, the old 180 degree error is all too easy.