Please note: Slim design, square yellow plug. This item is a high-quality power supply. It is ideally suited as a replacement or secondary device and provides power to your Lenovo ThinkPad W540 just like your conventional power supply, enabling reliable battery charging. Note: Unless we explicitly state that this is an original product, we supply a compatible product. This means it is by no means an original product from the manufacturer and is therefore not produced or recommended by them. All brand and product names are the property of their respective owners and are used solely for compatibility description.