3Pcs Yootones Guitar Soundhole Cover Soft Rubber Feedback Buster Compatible with Acoustic Guitar (Black)

["The guitar sound hole cover is compatible with most standard acoustic folk guitars; Bottom Dia: 4in.","The guitar sound hole cover is made of superior rubber,Soft, durable, high quality to use, safely inserts into your guitar sound hole.","The guitar sound cover can eliminate unwanted feedback and enhance stage volume without disrupting placement or performance. Protect the sound hole.","Pack of 3.Easy to install, without any tool required, convenient for daily life.","An ideal tool for the guitar enthusiast to eliminate feedback and enhance stage volume."]