That is a crazily good price if it is indeed £50
You’d need the clamps by the looks of it, and it’s very important to have the one with the nubbin to be able to support it so the bottom of the filter is kept off the heat shield as the noise is totally dumbed down if it sags. These can be bought direct from RamAir for £5 each (but you have to buy 2).
Would also need the blanking plug/condom for the inlet too.