Amazon.com's Prime Day sales were lower on the first day said Momentum Commerce. The company which manages online sales for 50 brands said its Amazon sales plunged 41% on Tuesday when compared with the start of Prime Day last year.

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Milwaukee’s two-pack of high-output batteries is another great deal, currently an impressive 50 percent off—a savings of $150—at Walmart. These 18-volt batteries are compatible with over 150 M18 cordless tools and have a 6-amp-hour capacity. They also come with overload protection and a three-year warranty.