I have a 2010 superb with electric seats, I'm about to install "loops" for a babyseat and they go where the rails for the seat is installed so I need to remove these, install the loops and screw them back in. 

 

What size bolt do I need to buy? 

I only have smaller ones. 

 

These are not regular torx right? 

That's an XZN socket head, probably M10 size. If you need to replace the bolt for some reason, a dealer will be able to get you the correct size.

 

For your child's safety, you would be much better off putting them in an i-Size compliant seat in the back.

My kid already rides in the back, just don't want to wrap the attachments around the backrest of the the seat, since that limits the adjustability. 

Thanks for the your input. 

Is this for the anti-dive strap (the one that loops over the backrest and attaches to the bar in the backrest)?

It's two straps that attach to the back of the chair and to the floorloops im about to install or around the front seat backrest