A set of 4 64K x 1-bit DRAM chips. 150ns access time.
These will either be new old stock, or recovered components – but in either case, they will have been tested in a suitable computer to ensure they are functioning correctly. This is an important difference to many RAM chips sold on eBay and the like, which are not tested – and there can be around a 5% failure rate on these 30 year old components.
These are 128-cycle refresh DRAM chips, suitable for use in the Dragon 32/64.