Features: quality of materials. Multi-functional: training pets, physical class,outdoor training,etc. Training will be effective with for sharp noise when pets hear it. Durable,portable,useful. A keyring on the tail can be fied on for key rings for carrying. Specifications: Specification: Material: Aluminum Alloy Color: Random delivery(if you bought more than one,the color you received is different or the same) Size: Approx. 4.6cm(1.81in) Package Includes: 1 Piece Metal Whistle note: NOTICE: Random delivery(if you bought more than one,the color you received is different or the same) Please allow 1-3cm error due to manual measurement. make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you