STI Aluminum License Plate Bolt Cover
The material is machined from solid aluminum, and anodized to prevent rust. In addition, the included silicon washer is sandwiched between the license plate and the cover.
Made in Japan from 2000 series duralumin the size is 21 x 7.8 mm (+ Silicon washer 0.5 mm)
Designed for use with Japan standard sized number plate bolts which are 10mm head.