This Calendar 29 icon is a responsive icon. This means that it's optimized for four resolutions, from tiny 16x16 until highly detailed 80x80. The style comes from the latest Microsoft Office, which makes it perfect for any Windows applications, in particular, those with ribbon toolbar control. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 15,100 icons, all in the same style and quality.
It's a square with 2 ring-like objects at the top, to indicate that it's a calendar that you would flip to change the date each day. There is the number 29 inside the square, to signify that it is the 29th day of the month.