The R2-Astromech top cap probably won't repair your rocket ship when you get stranded on a remote forest planet, but it is a standard 1 1/8 top cap in custom anodized titanium, and it includes a matching anodized titanium M6 bolt to keep the little droid in place. These top caps are made individually, by hand, and minor imperfections and inconsistencies will occur as part of the nature of the process. No two will be exactly alike.