Unfortunately, the MB559U3S-1SB is discontinued.The closest replacement we have for the MB559U3S-1SB would be the MB991U3-1SB, however the MB991U3-1SB only accept 2.5” hard drives. The MB991U3-1SB is a full metal external enclosure that connects via USB 3.0 and supports hot-swap capability. Here is the product page. http://www.icydock.com/goods.php?id=188
If you are looking for an external product that supports 3.5” hard drives, the closest replacement we have the MB662U3-2S R1 and the MB561U3S-4SB R1. The MB662U3-2S R1 is a trayless aluminium constructed drive enclosure and supports two 3.5” hard drives. It also has a built in RAID chipset for simple RAID 0/1, JBOD, and BIG and connects via USB 3.0. The MB561U3S-4SB R1 uses the same trays as the MB559U3S-1SB, support up to four 3.5” drives, and connects via USB 3.0 and eSATA. Here are the product pages if you need more information on them.
MB662U3-2S R1: http://www.icydock.com/goods.php?id=189
MB561U3S-4SB R1: http://www.icydock.com/goods.php?id=219
If you have any questions on our products, please let me know. Thanks!