Hi yes 2 per cylinder but if you shop around quite cheap. The maual says change at 100K miles but many have changed much earlier. I have done mine at 24K and on another XF 30K but when I removed them they still looked like new and I didnt notice any running difference in any way. You will need a long reach quality plug spanner and be prepared to graze your nuckles! It is made easier if you remove the six coils for access.