Hi, if you want to know exactly what it is call and see alex (ex castle craft) now at the chandlery in bridge stores at Loddon, i'm sure he'll be more than happy to advise you.
Paul.
Just catching up on these threads after coming back from the boat, unfortunatly the old webasto on mine is on its last legs, decided last night to order a new Mikuni, ouch! going back to boat on monday to rip old one out ready for the new one, will fit it myself so will let you know how i get on when it's fitted.