will this work with my surface pro 4 bought in 2017? Microsoft support said I need a 24 watt and don't want to harm my surface pro.

Yes, this charger will work with your Surface Pro 4. It is compatible with Surface Pro 3/4/5/6/7 models and supports the required output of 24W.

Questions & Answers: Surface Pro Charger, Power Supply for Microsoft Surface Pro 3/4/5/6/7/2017/Surface Go & Surface Book, Windows Surface Laptop Adapter (44W 15V 2.58A)

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Surface Pro Charger, Power Supply for Microsoft Surface Pro 3/4/5/6/7/2017/Surface Go & Surface Book, Windows Surface Laptop Adapter (44W 15V 2.58A)

? Input: 100-240V 50/60 Hz; Output: 15V-2.58A 44W; USB port 5V-1.5A. It works with 15V-2.58A 44W and 15V-1.6A 24W and 12V-2.58A 36W
?Power Adapter for microsoft surface tablet charger, surface laptop 2/3 charger, surface pro 3/4/5/6/7 charger, surface go charger, surface book 2 charger.(All M3 I3 I5 I7)
? With additional USB 2.0 charging port of 5V / 1.5A. You can charge another device such as a phone at the same time.
? Built-in IC chip technology provides overload / short circuit protection / overload protection / heat protection. We test each charger to ensure a tight, strong magnetic connection. We have also sourced a very high-quality material to ensure our power adapter ends will never come loose and its wires will stay intact and remain safe from fraying, even after numerous bends and laptop charging sessions!