- The most reliable and hassle-free instrument strap lock system ever devised<br /> - No need to remove or replace existing strap buttons on your guitar; just slip easily installed Strap Blocks over the existing strap buttons and that s it you re ready to go, with your strap locked securely in place<br /> - Strap Blocks work with most OEM strap buttons<br /> - Available in convenient four-packs containing one black pair and one red pair<br />