Sump plug boss, for modifying DB2 & early DB2/4 sumps that had the boss / plug placed on the rear tapered part of the sump so you couln't get all of the oil out, use this & put the boss on the flat part of the sump so you can get all of the oil out.

By the time the later 3 ltr engines were produced Aston Martin had put the boss / plug on the flat so you could get all the oil out of the engine or would have been able to if they hadnt put half the boss inside the sump !!

It's easily silver soldered, braized or welded into the sump. this, used with the 'oil level sender' blanking plate is how the sump itself should be, leakless.