yellow plugs?

I am putting my disco back together. I have chequer plate for the inside of the back door. There are yellow plugs in the door that the fixings screw into. Problem is, i have no idea what the fittings are and after trying a few things, i've given up and come online!

So, anybody know what fixings i should be using? Bolts, self tapping screws? Any idea of size?

Cheers

They are sarated plastic plugs that slide into holes in the door panel then they just push fit into the yellow things, i would just ignore them and just use some self tapping screws to hold it in place, if your plate is around 5mm thick a 10 or 15mm screw should be fine just be careful where you drill the holes so you dont hit anything behind them

Perfect, thank you!