This Sand Clock icon is made in Material Design style developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 4,400 icons, all in the same style and quality.
Imagine the top shape of a wine glass without the stand and base, and now imagine another one that is upside down and they're both connected. Both of the openings of the whine glasses are enclosed from the top and bottom. There is space in the middle for small objects to pass through.