Don't you hate when water splashes out of that hole in the Yeti tumbler lid? Well now you have a solution to that! This is a plug for the lid in the Yeti Tumbler lid. Comes with elastic cord that you can tie to your mug so that you do not lose the plug. This plastic part is 3D printed out of PLA plastic, so please do no place in the dishwasher. this is designed (and works) to prevent water from splashing out when in the normal upright position. It is NOT designed to be a 100% seal when you dump the cup completely upside down! Even if it worked for that, there is a small hole in the lid of the Yeti cup where it will leak out (that hole is on the opposite side of the drink hole and is needed to allow air out when you drink)