Step 1. please check the input data on your laptop or your adapter output. You will find voltage and current data. Such as 20V 3.25A 、19V 3.42A、19V 2.37A.... Step 2. check your connection plug size. Out diameter * lnner diameter Such as 5.5*2.5mm、4.0*1.7mm、 4.0*1.35mm.... If still not understand ,please ask help from us !