This portable charger has been posted in SD before, as recently as 1/11/18 which was a frontpage deal https://slickdeals.net/f/11145155-ravpower-20100-portable-charger-with-qc-3-0-type-c-battery-pack-34-99-fsss?src=SiteSearch
That previous deal was cheaper by $5, but did not include the bundled wall charger which looks to be solid or the USBC-C cables. Here is the link to the current deal.
To get the deal, click the link and then look under the available promotions on the product page. Add both to cart and you should be good to go for $40 (plus tax)
I actually bought the battery last week as a warehouse deal and would not hesitate to buy it again if I needed another one. The battery itself has a quick charge input so the huge capacity was able to fully charge in 4-5 hours. It also provides a quick charge for QC 3.0 compatible devices as advertised.