I'm looking to retro fit rear parking sensors in my missus' Astra.

Can anyone recommend a set??

Also, does anyone know if the Astra will have the bumper premarked on the inside, as the Veccy does, and what exactly will i need (in terms of rubber mounts for the sensors etc...)?

Thx guys

EDIT: It's a 2004 Astra convertible if its makes a difference???