These expansion cards work in either Microsoft’s Xbox Series S or X consoles. | Image: SeagateIt’s easy to run out of storage on your Xbox Series S or X when a single game can eat up over 100GB. The best (and pretty much only) solution is to buy an expansion card from Seagate or Western Digital. You can store Xbox games on a USB external hard drive, yes, but you’ll need to re-transfer them to the system’s internal storage to play them. An expansion card allows you to play games from your library without having to move anything around.Fortunately, you can pick up a 512GB WD Black C50 expansion card for $85.99 ($8 off) at Amazon, which is its second-lowest price since May. Western Digital’s 1TB expansion card is on sale for around $119.99 ($30 off) at Amazon and Best Buy, which is its lowest price since July, though it’s $20 shy of beating that price.Seagate’s storage expansion card, meanwhile, starts in a 1TB configuration, and is discounted to around $123.49 ($30.50 off) at Amazon and Best Buy, which is lower than it was last Prime Day. If you need even more space, a 2TB card is on sale for $199.99 ($160 off) at Amazon and Best Buy, which also bests its previous Prime Day price. Seagate’s 4TB expansion card (the largest size configuration available from either company) is down to $379.99 ($120 off) — a new all-time low — at Amazon and Best Buy.These cards fit into a slot behind the Xbox and match the read and write speed of the console’s internal drive, so games will run without technical compromises. There are no cables to plug in or compatibility issues to worry about. The number of games that’ll fit on the card will depend on which card you get and what games you play; Fortnite requires just over 86GB of space, while Stardew Valley takes up 1.53GB.Seagate Storage Expansion Card for Xbox Series X|SSeagate’s Storage Expansion Card is as fast as the Xbox’s internal storage, comes in 1TB, 2TB, and 4TB sizes, and fits into a proprietary slot without any cables. Where to Buy: $159.99 $123.49 at Amazon (1TB) $349.99 $199.99 at Amazon (2TB) $499.99 $379.99 at Amazon (4TB)Western Digital C50 Storage Expansion CardWestern Digital’s C50 is a storage expansion card for the Xbox that let’s you add between 512GB and 2TB of space for digital games without impacting their performance.Where to Buy: $93.99 $85.99 at Amazon (512GB) $149.99 $119.99 at Amazon (1TB) $149.99 $123.49 at Best Buy (1TB)If you’ve committed to only buying digital games, tripling your total storage will prevent you from having to download, delete, and redownload titles, which can take hours depending on your internet speed. Even physical games can require big day-one patches to run. A storage expansion card is all but essential for Xbox Game Pass subscribers because new digital games are added to the service monthly.