{HEAD ~ The palladium} based three way catalyst may be palladium or palladium with {TAIL ~ another noble metal} like rhodium 
{ HEAD ~ The palladium } based three way catalyst may be palladium or palladium with { TAIL ~ another noble metal } like rhodium
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH