Aprilia Bar End Weight Holders AP8121520
Fitment - RSV 98-10, Tuono 02-10, Tuono V4 11-21, RS and Tuono 660, Shiver 07-10, Caponord 1200 14-17, 1200 Rally 16-17
Genuine Aprilia bar end weight holders, part number AP8121520, item number 2 in the diagram.
Used to attach the actual bar end weight that will help reduce the amount of vibrations felt whilst riding. They simply screw in to the original clip on and handlebar of your Aprilia and then the actual bar end weight screws into this.
There has been a lot of R&D by motorcycle manufacturers to try and limit the amount of vibrations the rider will feel and so the OEM ones are specifically designed and weighted in order to achieve maximum capture of those vibrations. If you replace them with aftermarket ones, you may experience more which could result in a less comfortable ride.