Just check coupons out (with price alert and history). You probably want to know what is the best price?
Name Diving Oxygen Cylinder Set, Max Pressure 3000PSI/200BAR/20MPa, Bottle Capacity 1L, Bottle Material Aviation Aluminum, Underwater Breathing Time about 15-20min, Bottle Size 40.2×8.5cm/15.83″x3.35″, Color Black
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in Europe 
. Well, there is one coupon available right now.
Link: Banggood product page
1. ($253.79): BG589b2e
coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGc43af6, pROMo8cuPoN, BG23da17, BGfc8a9a, BGa61f2e, BGcf0106, Cuponation9, BG073996, BgGoodie9, BGc363fd, BG6f1ef9, TTBLACK5, JanBGCoupon8, BG4a6a62, BG2830a5, BG2623b9
(there’s a little possibility that old coupon will work)
Price history and price alert
Here is price history (for all/most countries) for DIDEEP X4000 Pro 1L Scuba Diving Tank Set [EU].
Price records source(s): Banggood
Click on image to enlarge. ![Price history for DIDEEP X4000 Pro 1L Scuba Diving Tank Set [EU]](https://couponsfromchina.com/pricehistory/History35256.png "DIDEEP X4000 Pro 1L Scuba Diving Tank Set [EU] price history")
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).