[Ad size] 300x1050 [Text ads] ✓ [Display ads] ✓ [Description] 
Also known as a "portrait". A brand-centric format that performs well when placed non-intrusively alongside content on the left or right side of the page. This format integrates well with the content and layout of most websites, and provides advertisers with the ability to create engaging, creative content within this ad unit. While demand from advertisers for larger ad formats is on the rise, the supply of available display ads for this ad size is currently limited.