Making the filters sell: attach rate from 18% to 54%

Hardware brands in this category make their real margin on the consumable, and this one was giving it away. Its filters had thin listings with no model-number coverage, no subscription, and no connection to the purifier listing beyond a line of text — so when a customer's filter light came on nine months later, the search “filter for model” returned four compatible third-party options above the brand's own.

The purifier listings also never mentioned the replacement cycle, which meant the brand had no opportunity to set the expectation that a filter is part of owning the machine.

We connected the machine to its consumable at every point where a shopper could fall out.

• Model-number coverage — every filter listing indexed for the exact machine names and part numbers people actually type.
• Subscription on the filter, with the cycle length stated on both the purifier and the filter page.
• Bundles at purchase — machine plus a spare filter, which sets the replacement habit at the moment of the original sale.
• Targeting the brand's own installed base — Sponsored Display aimed at previous purchasers approaching their replacement window.

The attach rate went from 18% to 54%, taking consumables revenue from $41k to $132k a month.

Because filters carry a much better margin than hardware and cost almost nothing to acquire, this is the most profitable 40% of top-line growth the brand has had. The repeat purchase rate more than doubled, which also changed how the brand values a machine sale: it is now the start of a relationship rather than a single transaction.