As great as posters are, they look so much better inside an A1 frame. The frame keeps them from rolling and makes them more presentable.
A1 frames are for posters that are 84.1 cm by 59.4 cm in size, so be sure to measure the poster before getting the frame. Consider the A1 frame, itself; choose the border's colour and width. Get all of those collector’s posters into something more presentable.