These are the same type of rings that can be found on a Land Rover Defender factory audio system set up. These are perfect for pre 2002 Td5 model Defenders where there can be a speaker compatibility issue with the wiper motor on the lower dashboard. These rings add extra space to the area directly behind the speaker. They are also stackable if you wanted to use more than one ring to create more room behind the speaker. Depth is 14mm. The spacers are sold in pairs. The fixings are not supplied.