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Solar panel power: 28W, Conversion rate: > 23%, Quantity: 4 PCS, USB output: 5V, up to 2.4A per port and 4A total under direct sunlight
Aliexpress
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Here are coupons that you can use.
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Price history and price alert
Price history (for all/most countries) for Zanflare SH54 28W Solar Charger is here.
Price records source(s): Gearbest
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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)).