Special rubber ferrule (seal) used on the external oil pipe of 12A-series 1275 engines (1992-96). This is a genuine Rover seal as originally fitted. Two (2) fitted per car, sold each.
As an alternative, you can use an improved ferrule LZV100080, which is aluminum and not prone to leaking.
In performance applications, the external pipe is often replaced with MOC1018 braided stainless pipe for enhanced reliability.