Laptop memory (SODIMM, the short module) and desktop memory (DIMM, the long one), in DDR4 and DDR5. The two generations are keyed differently and do not fit each other's slots.
Match the generation the machine takes: DDR4 boards take DDR4, DDR5 boards take DDR5.
Priced per module.
Minimum order 50. 10% off over 250, 20% off over 500, on one line.