Feature: 1. [Semi Closed Design] This guitar string tuning knob features a semi closed design that better protecting the strings from slackening or skipping, providing more stable musical performance during playing and tuning. 2. [Enhanced Tuning Stability] This guitar string tuning knob has a good locking mechanism, which ensures that the strings stay in tune during playing, avoiding frequent tuning or string slack. 3. [Zinc Alloy Material] This guitar string tuning key is made of zinc alloy material for durability and stability, which can withstand longer use without losing performance. 4. [Easy Installation] This guitar string tuning knob is very easy to install, just remove the old string knob and replace it with the new one, no extra tools or complicated steps required. 5. [Widely Applicable] This guitar string tuning knob is suitable for all types of electric and acoustic guitars, both electric and acoustic guitars, providing stable and reliable tuning results. Specification: Item Type: Guitar String Tuning Key Material: Zinc Alloy. Package List: 6 x Semi Closed String Knob6 x Nut Sleeve7 x Screw