5618 Ernie Ball Guitar Strap Blocks Locks 4 Electric-Bass-Acoustic PURPLE   Securely fasten your strap to any instrument with Ernie Ball rubber strap blocks. Fits most strap button types and provides a tight fit without any modification to your guitar. Made of flexible, durable rubber that will slip over existing strap buttons for a secure connection.    Easy to install.  Secure fit.  Made from durable silicone rubber.  Fits most strap buttons.     FAST & FREE SHIPPING!