This is a two-pack of straw adapters for your 20/30 oz Yeti Stronghold lid with two-piece slider. Our adapter fills out both openings on the lid, as well as having a retaining lip to prevent movement of the adapter while in use or when changing straws. Additionally, the straw hole has a four-tab retention design, to prevent movement of the straw when installed, providing a more secure user experience. To install, simply remove both pieces of your Stronghold lid, and starting at the smaller opening, press the adapter firmly into place on the top of the lid. To remove, press on the adapter firmly from the bottom side. Made of flexible 95A TPU.