Just check coupons out (with price alert and history). Do you want to know what the best price is?
Color Black, Brand KALOAD, Material Elastic webbing, child, Battery 250mAh, Apply to Adult, Strap size 55*3cm, Angle setting 5-50° adjustment, Product size 108*81*16.5mm Adjustable
Aliexpress
I could not find it on Aliexpress. Click here to search by yourself.
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one coupon right now! Check this out.
Link: Banggood product page
1. ($22.79): BG00c906
just apply this code in your 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): BGG68285, BGSHHA, BGDG68285, BGSDG68285, BGF68285, BGSDSS, BG10OFFAFF1, BG4d9120, BGAlerabatod, 00c906
(probably won’t work, but you can try them out)
Price history and price alert
Here is price history (for all/most countries) for KALOAD Smart Back Posture Corrector.
Price records source(s): Banggood
Click on image to enlarge. 
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)).