These are clearly much better than typical auto parts store cables. I purchased these to keep in my RAM 1500. The more common, smaller gauge cables wouldn't boost the batteries found in these types of vehicles, so heavier gauge cables are a must. I see some mention of them being copper clad aluminum vs solid copper cables. The Service Entrance cables from the utility pole to your home are aluminum - not copper and not even copper-clad aluminum. For the person looking to boost most types of vehicle batteries encountered, there's just simply no need for anything more than these. These are "heavy duty" in the sense that most vehicles can be jumped by using smaller 6 or 8 gauge cables - these are a larger gauge, hence can be called "heavy duty" (Reminder...the smaller the number the larger the gauge and thicker the wire). These are built well, the clamps are versatile, insulated well and more than heavy enough for most scenarios. I used them once so far over the winter - not terribly cold - maybe upper 20's (F) to jump a Jeep and they worked and handled well. The additional length is a huge convenience, especially with a larger vehicle such as mine. You don't have to worry about positioning the vehicles just right to use them. They came with a pair of gloves and a small wire brush for cleaning terminals. Not essential, but a nice touch. The carrying bag is sufficient for a typical few-times-per year use, and the cables should provide years of use if stored responsibly and not used to tie-down cargo or if hastily rolled-up, tangled and thrown in a trunk. If you are performing regular recovery service you would need a better carrying case. Also - they are not intended to be pulled-apart, as the jacket is not perforated and will likely tear and expose the conductors. If you want cables that are completely separate you can find and purchase them that way. Not sure why someone would alter the product then ding it for failing. I wouldn't pay much attention to some of the over dramatic negative reviews or the one's complaining about copper-clad vs pure copper conductors. Those differences are applicable for precise electronics where every watt and milliamp count and extreme efficiency is needed. Boosting a battery requires sufficient voltage and current for a relatively short time, and nothing more. I spent 10 years in the electrical trades and now do design work which entails calculating current, voltage drop and ampacity. In my opinion and experience, these are a good purchase overall for what they're designed for.
NOTE: I purchased this item on Amazon for full price and have no affiliation to the seller. I try to write helpful, unbiased and insightful reviews because I also read reviews prior to making my own buying decisions. I notice many reviews lack helpful information, are not well written or give poor reviews based on not reading directions, inexperience or failing to read the product details prior to purchasing. Writing valuable reviews helps pay it forward.