If you want a good tool, buy name-brand.
As others are saying, this set of ends and tools is very cheap and not build to last. The hinges in the crimping tool aren't riveted and slide out, allowing the tool to fall apart. The F connectors also fall apart quite easily. I had to crimp some quad-shield RG6 which I thought may have been incompatible, but it is possible to do and get good signal. Once the cable is cut and trimmed properly, gently start twisting one of the ends on to it. More than likely, the bottom shell of the connector will start to slide off of the inner core. At this point, insert the end of the cable into the crimper making sure to apply pressure to the inner core of the connector. If that doesn't work, use a small flathead screwdriver and a hammer to tap the inner core so it sits fliush with the dielectric of the cable. You may also need to put the end back in the crimping tool, and use the screwdriver + hammer to tap the crimping shell back down so it sits flush with connector screw head. After that, you may need to crimp twice, flipping the cable 180 degrees to get both sides of the connector's collar.
Long story short, stick to buying name brand tools if you want them to last.
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