So my friend gave me her sons infant car seat since he has long outgrown it but she couldn't find the base for it. It is a Britax but I'm unsure of the exact model as there was no owners manual or anything since it's a couple years old. However I was looking it over today to find a serial number to get more info and noticed instructions on the side of it to install without the base, just using the seat belt. I did some research and found outnhow to properly secure it in my car like this but my question is is it ok to have it installed without the base permanently or are there rules or anything saying that it has to be used with the base and is it less safe to not use the base? I can't imagine that the company would put any kind of installation recommendation on it if it wasn't safe, but idk this is my first child so I've never dealt with this stuff before!