I use these to work with the c tek lithium battery tender I have. I dont want anybody hooking up the wrong battery tender on my bike so I use these.What I don't like is the red and black wires I think is ugly. I get the Importance of polarity but I still don't like it. I put tech flex over mine and used shrink tube. I had to extend the wires on mine anyway.All in all good product and I recommend.This is one smart product. If you havent bought this yet, what are you waiting for? Buy it you wont regret.I purchased the CTek Multi U.S. 3300 Battery Charger for use on my three automobiles and riding lawn mower. I have the Ctek 56-261 Comfort Connect 3/8" Eyelet cable on my SUV and mower batteries. It is comforting to know that I can leave my mower charging all night or longer without removing the battery from the mower and it is perfectly safe. I am ordering two more cables to put in my wife's SUV and daughter's pick-up. If they need to charge their battery while I am away all they need to do is snap the connector to the charger's cable, plug in the charger then set the mode on the charger to Automobile. No worry about reverse polarity, sparks from clamps, improper grounding or clamps coming off. The 3/8" eyelets fit on the battery post clamps on all my vehicles. No need of boring out the hole to fit the bolt on the clamps. Plus, if you are away from home and need a jump the connectors can be left in place while standard jumper cables are used. Another plus, more so for the charger is it is so small you can take it with you on a trip where as a standard charger takes up too much space. This is a great system and the tech support is top notch. The only negative is the cable is somewhat short but I am sure that is by design to keep it away from moving engine parts while the vehicle is in use.It works, and should be slightly more convenient than the terminal clamps that the Ctek charger comes with. But it is too short to extend from the battery through the grill of our 4Runners as hoped. Also, these cables are not fused, which seems odd since the terminal clamps are fused.This extension cable is almost perfect - the only change I would make (leaving the price alone) is to make the cable longer. It would be nice to be able to fish a longer cable through the grill or cowl area so the hood doesn't need to be opened to connect the tender.It doesn’t have a fuse like the original one we l that came with the charge. That’s why I have a 4I might have got defective parts. Sending them back and trying again. Easy to use. They just need to work! Ctech is the best brand. So I'm giving it another chanceIf you've even tired to access the battery on a Polaris Sportsman you'll know what these are worth their weight in gold... having struggled to access my battery3 times this purchase was a welcome addition...We use these on all our cars including our electric cars Tesla & Leaf (by law they are required to have a 12v lead acid battery, all that tech weighed down by idiots in power where another Lithium ion battery could have been utilised.But hey ho, these things are simple to fit & are on all our cars, if you have a merc with a floor based battery this speeds up access & charging faff, if you have a smart car with the battery under the passenger footwell one of these ctek's allows it to sit in the middle of the trim to charge it from either side of the vehicle.Idiot proof for the idiot generation who have to call out the emergency services to change a tyre or similar, the cable also acts as a visual reminder to do a battery maintainence charge periodically & also renovate (shake cack off the plates).This is a buy once use forever product, cheap enough, (often one comes with a ctek charger too)Get one (no need for the LED version they aren't accurate & so misleading)K.I.S.S.Rubberised & idiot proof.Consider buying a USB lighter socket voltage display to give you additional warning when you start your car up as to voltage (my eyes are always on them, they work) used in combination with a ctek you can pre-empt voltage drop problems & get in there before winter / lack of use damages your batteryI think the Ctec battery charger is a brilliant piece of kit especially with the battery drain on most recent vehicles where mileage is low.Unfortunately Ctec only supply one set of terminal extension wires (they do provide standard crocodile clips but this involves removing battery covers) which can be routed to an accessible point with plug in connection.Bought these for second car. My only criticism is that the wires could be perhaps be a little longer.I wanted to use this connector to fit my battery bolts so that it's easy and safe to connect my charger even in low-light conditions. It's a simple fit - disconnect the battery clamps, (black/negative first, red/positive second), then fit the corresponding coloured lead to the terminal bolt and then replace the clamps in reverse order, (i.e. red/positive followed by black/negative). Once complete and firmly tightened, plug the Ctech lead into the socket of the connector and switch on. Lovely.These instant connectors/daptors are a great idea (esp if eg your car had a rather inaccessible battery compartment....). Silly me, I didn't know that the '10' or '6'' options referrred to the diameter of the connections to the battery - as I would have preferred the '6mm' ones. But the '10s' still work and it's a neat little idea to make eg multiple units attachabe with minimum hassle.Note these are made up items of course, which is expected at price, stiff wire etc, but eyelet is not as pic, they are large hole and very thin, so flop about on normal motorcycle battery terminal, have to use washer ideally, not just tag on directly. No fuse of course, as per pic. Half price of genuine, so make the choice...