The Original Instant Thumbscrew The Shear-Loc process is a unique and cost effective way to convert standard socket head cap screws into instant thumbscrews.For over 50 years we’ve been dedicated to producing high quality products right here in the USA and distributing them worldwide.We offer 10 different styles with 5000+ combinations to meet the needs of your application.Test before you invest. Contact us for FREE samples! Product Lines Knobs Only Knob Kits Thumbscrews Key Drive Thumbnuts In-House Laser Click the reference guide above for a printable PDF.