Tradesy filming a second series of commercials in partnership with Guthy Renker.

Designer resale site Tradesy is getting a boost from ads on TV.

Direct-response marketing company Guthy Renker, known for its Proactiv infomercials, has become the exclusive direct marketing partner of the four-year-old site, putting together a series of Tradesy TV ads that began playing last month on two dozen networks, including E! and Lifetime. The effort was successful enough for the resale destination, which boasts more than five million members, to go for a second series of commercials with Guthy Renker.

The messaging was strategic, according to Tracy DiNunzio, founder and chief executive officer of Tradesy. The current commercials are focused on getting women to sell their designer clothing and accessories on Tradesy — and the new batch, debuting during the second quarter, will be targeted toward buyers.

The first set of spots all showcased how a potential seller can list merchandise straight from their closet, and has since brought new sellers onto the platform.

Tradesy is among the leading resale e-commerce sites. To date, the venture has raised close to $44.5 million, and counts Richard Branson and Kleiner Perkins Caufield & Byers as investors. The site’s average order value is about $300 and the DiNunzio forecasts that the site will facilitate more than $300 million in sales by year’s end.

“It’s challenging for tech companies to understand media buying and what they call attribution — figuring out which traffic came from where,” DiNunzio said. “It’s hard. You can have a mention on a TV show on Good Morning America and then you have TV commercials and traffic from all sides. Which one did people respond to?”

This is where Guthy Renker comes in. Beyond direct marketing, the company is able to track its products through the whole life cycle with a detailed attribution model. Guthy Renker can analyze a Tradesy commercial and figure out how much it costs to get a customer to the site and offer insights into the customer throughout their lifetime. That allows the company to tie advertising cost to the earnings from that customer.

Boris Shimanovsky, creative director at Guthy Renker, said the company buys a quarter of a billion dollars of TV ad space per year and has a knack for speaking to women consumers.

“We’re not in the fashion business at all, but we understand women are really passionate about fashion,” said Shimanovsky, adding that once someone has a positive experience with Tradesy, they come back for more. “It’s a great continuity model. They tend to buy more things or sell more things and are able to use the platform and share the platform with their friends.”

As far as results thus far, DiNunzio is able to assess how successful a commercial is by looking at metrics for cost per visitor or cost per seller.

“Both of those are now the same or lower for us on TV as they are online — which is pretty much unheard of,” DiNunzio said. “The general attitude of tech companies and emerging fashion companies is that TV is just too expensive a medium, but we’re finding that compared to very common Internet mediums of adverting like Facebook or search, we’re able to rival those costs while advertising on TV. We’re measuring it against all of or other advertising channel on a sales basis. It’s succeeding on that measure.”