Battery Capacity(mAh): 400mAh, Working Time: 4 – 6 Day.
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Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. As you can see I didn’t find any active coupon for this product right now…
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): e2bcea, BgAuMotor, b71c67, AM15prime, AMPrime01, BG7705, BGAutos, BGCS10, BGSP63, bGhOnEy10, BGCARELEC, BGCARPRO, BGGF074, BGAFF10OFF, BGCuponation10, BGb77b8b
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for GF07 Magnetic Tracking Locator. The lowest price was: $4.59.
Price records source(s): Gearbest, 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)).