There are thousands of anti-aging skincare products on the market that promise to banish signs of aging and dull skin, but the number of formulas that deliver isn't as broad. This antioxidant serum with a dash of retinol is one of the few that actually does, according to shoppers, and even though Cyber Monday's over, it's still on sale for 20 percent off.

Paula's Choice Super Antioxidant Concentrate Serum with Retinol promises to refine skin, defend against signs of aging, and eliminate dryness. The antioxidants in the serum are responsible for brightening dull skin damaged from environmental stressors. And thanks to a blend of grape seed extract and olive fruit oil, the lightweight serum adds moisture without leaving a greasy residue or clogged pores, completely absorbing on contact.

Shop now: $29 (Originally $36); paulaschoice.com

It also has a small amount of retinol, a derivative of vitamin A that assists in cell turnover, at .01 percent. The well-researched ingredient helps "with acne, brown spots, sun damage as well as fine lines, wrinkles, and textured skin," esthetician and co-founder of Glo Spa, Aishe Balic, previously told InStyle. "As we age, our collagen begins to break down, and [retinol] encourages collagen production," Balic explained. "But it can also help people suffering from acne and clogged pores because it reduces oil production. Sun damage can also be brightened with retinol as well because of sped up cell turnover."

Shoppers are thoroughly impressed with their results. "To say I love this stuff would be an understatement!" one wrote in a Paula's Choice review. "I love the smell of it, I love the way it leaves my skin feeling and just everything about this. I use it every morning, and it's just so refreshing." They added they "will never stop using" the retinol serum.

"I have been using this product for 18 years," another reviewer wrote. "I am 64 years old, and my skin is so smooth and barely any wrinkles. People are always asking me what [I do] to my skin and if I've had any work done. I love it, too, because it moisturizes my dry skin."

A final shopper noted that the serum is "basically witchcraft." They added: "This serum is bizarrely effective. It doesn't burn or irritate my skin. It doesn't cause breakouts. But even more amazingly, the healing cysts are healing way faster now, and the redness is dying down quickly."

Head to Paula's Choice now to stock up on the Super Antioxidant Concentrate Serum with Retinol while it's 20 percent off.