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Nest smoke alarm 4 for 360$. $360
Buy 2, get $40 off or Buy 3+, get $80. Valid 10/18/21-10/24/21. Online-Only. While supplies last. Limit 2 discounts per membership.
When you add two counts (of 2 pairs totaling 4) of Nest smoke alarm the price drops to 360$ with 40 discount.
May be you can add a boss speaker ($149 - Bose SoundLink Mini II Special Edition Bluetooth Speaker) for another 40$ discount.