model device The laptop model is usually located on the bottom of the device. Read it and enter it into the shop's search engine. e.g. Asus K53SV / HP Pavilion G6 / MacBook Pro 13 A1278 value of INPUT / OUTPUT On the nameplate of the power supply, the voltage and current values are marked as OUTPUT, and on the bottom of the laptop the same parameters are marked as INPUT. Read some of them and enter them into the store's search engine, adding the brand of the device to them. Make sure the plug of the found power adapter is correct. e.g. Asus 19V 4.74A / Dell 19.5V 4.62A / Lenovo 20V 3.25A.