A: The Spider Drive was developed as an alternative to 6-lobe options. It provides greater vertical locking features than many of the star shaped options that tend to be a "sloppy" fit inside the recess. We do provide a free bit in every package, multiple bits in our larger quantities. The two-pack of bits you inquired about are meant to provide an option to customers who lose the original bit. It also is designed to accept both a #3 Phillips or #3 square drive as an additional option.
A: I'd say this is larger than even the T20. It will be too big for your application.
A: "compared to?" a completely different type of bit. Square, Phillips, Flat, Torx, Spider. Go look at your Torx bits and fasteners, and count the ribs. If they have 6, they are Torx, NOT Spider.
A: I doubt this will fit. I have a Hallmark trailer with screws with an 8 point head. Torx doesn't make a bit between 15 and 20T. I used a #2 Robertson screwdriver, which worked fine. If the screw is too tight or rusted in, I used a pair of vice grips to loosen it, then used the Robertson. Worked great.
A: Yes they worked well.
A: Yesss it is perfect for thise kind of impact drills