The first is Albemarle Corp, which reported a blowout quarter that sent the stock soaring 10 percent Wednesday. Albemarle makes technologically advanced specialty chemicals for various industries, including rechargeable batteries.
The second member of the dirty-half dozen is AptarGroup, a top player in the packaging industry that makes dispensing systems for products in the beauty, personal care, home care, pharmaceutical, food and beverage markets. The stock is up 15 percent since January lows, which Cramer attributed to the weakening dollar boosting the company's 56 percent of sales in Europe.
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Next was Carlisle Companies, a diversified manufacturer of products for smaller markets that include roofing, construction, energy, mining, foodservice and transportation. While many wonder why all of these businesses are under one roof, Cramer pointed out that the decentralized model could be benefiting the company.
It has a history of making smart acquisitions and then providing leeway to the management teams at their subsidiaries. With the stock up 32 percent since February, it has continued to roar higher.
The third overlooked industrial is Parker-Hannifin, which may be familiar to some. It is a diversified manufacturer of motion and control systems for the industrial, aerospace and mobile machinery markets.
Parker-Hannifin was hit hard, with the stock falling to $83 in January from its peak at $132 in November 2014. However, during that time it managed to cut costs, and with the dollar getting weaker and end markets improving, the stock has bounced back more than 30 percent since January.
"I think it's got more room to run," Cramer said.
Next was RPM International, the maker of paints, coatings, sealants, roofing systems and specialty chemicals. Cramer pinpointed RPM's strength to it being a very skilled roll-up with a long track record of smart acquisitions and helping those businesses thrive.
The last dirty half-dozen player is Rockwell Automation, up 27 percent from January lows. The company sells power, control and information solutions used for industrial automation. The stock stalled after a strong run about two years ago, and then went into free-fall from last summer to January.
Rockwell came roaring back after reporting two strong quarters in a row, and Cramer suspects it could continue to climb.
Ultimately, all of these under-the-radar plays have one thing in common, Cramer said.
"The one trait they each share … is that they are all vital to their customers, and as the environment improves, I bet that spells success for all of 2016."