Product Number: base 00003 Handmade genuine leather (cowhide) Saikol Special Cover Model The Saikol whistle from Sanwa Seisakusho, which produces a sound even with a light blow. This "science whistle" is a disaster prevention and crime prevention whistle that emits a 3150Hz sound, the easiest frequency for the human ear to hear. Since many people are embarrassed to carry just the science whistle, we are selling it as a special set with a special genuine leather cover m(_ _)m Because it is designed specifically for the Saikol, you can change the color variations by purchasing different colored Saikol whistles (*^^*) You can coordinate it in various ways, such as on a bag or belt loop. This product is a 520BASE (Gonimaru Base) original product m(_ _)m ※ This is not a project of Sanwa Seisakusho. I fell in love with this whistle, which is a very wonderful product, and designed and manufactured it myself, just because I wanted it in a style I liked (*^^*) The number of people who want it has been increasing on social media, so I will be listing it on Mercari m(_ _)m ※ Please note that this is the Mercari-exclusive price m(_ _)m - Model Name: Genuine Leather Whistle Cover with Saikol - Color: Green - Material: Leather - Decoration: Turquoise decoration - Sound Frequency: 3150Hz Thank you for viewing.