Review on Enhance Your Harley's Performance with the Alpha Rider Pro Carb Rebuild Kit and Mixture Screw: Compatible with Keihin CV CVK Carbs for Harley Big Twin 1990-1999, Twin Cam 1999-2006 & Sportster XL 883 1200 1988-2006 by Victor Garro

Mixing screw appears to be a finely crafted part. The kit included a new spring, washer and O-ring. The upper part is surface machined on the knurled side. There is no marker to monitor the setting. I used a file to make a notch on one edge after inserting the screw so I could count the number of turns. I believe it is a brass alloy as it is fairly easy to work with small chips. It didn't feel like it would cut too easily, so considering the fact that it's a 'set it and forget it' sort of thing, it should go on fine.