HUB75B is not available any more. You can buy HUB75E from this link:  HUB75E card. 

HUB75B HUB Card works with LED display modules of 1/16 duty, 1/8 duty, 1/4 duty, 1/2 duty and 1/1 duty.  Please check the following HUB75B pin definition before you order our HUB75B card.