Custom seat bases

Anyone know if these sort of things are okay to use?
https://www.ebay.co.uk/itm/124523175686?hash=item1cfe28df06:g:UMAAAOSwe~1ejCvM
 

I suspect it depends on which type of after market seat you are going to use.

If you have a Four door, or a Two door then make sure that a Two door, your replacement seat can fold forward.
Also if your aftermarket seats have glides on them as there is no adjustment on this base, so your replacement seat should have
runners or glides.
 

Good points. I was thinking of the Recaro LS-C. Will look to see if they have sliders.

Are these sort of bases 100% safe?

I know this is a year old but how did you get on with finding some bases? 

I'm in the same position and I am looking at some Recaro ls's but none of them come with any bases. 

I have purchased these base and you can mount directly to them or get some Universal runners and sandwich them between seat and base. This will also add 25mm depending on runnera you use. On a positive note they have a few different hights and angles you can use to get it as comfy as possible