Usually microfiber cloth will do. I've been cleaning ND filters with a Dslr cleaning kit:
https://www.amazon.com/Altura-Photo-Professional-Sensitive-Electronics/dp/B0098QH2BC/ref=mp_s_a_1_4?ie=UTF8&qid=1527662412&sr=8-4&pi=AC_SX236_SY340_FMwebp_QL65&keywords=dslr+altura
Link: DJI Officially Releases Ronin-S Gimbal for DSLR & Mirrorless Cameras!
It'll now be easier to combine stabilized DSLR/mirroless camera footage thanks to DJI's newest gimbal. Who's interested in buying one? This can be a game changer for travel vloggers!
I ordered 10 Phantom 4 Pro low-noise propellers straight from DJI, so I'm keeping two sets and selling the rest. All I ask is $10 for each set ( 2 propellers) plus however much for shipping.
If you buy it directly from DJI, shipping can cost $15.
The thing is I just placed an order today, so...