Circor International (CIR - Get Report) said Monday its board had unanimously rejected a cash tender offer from Crane (CR - Get Report) to acquire Circor's outstanding shares because the offer "substantially undervalues the company."

"The Board unanimously recommends that shareholders not tender their shares into the offer," Circor said in a statement. "In reaching its recommendation that shareholders reject the offer, the Board, in consultation with its financial advisors, determined that the offer substantially undervalues the company and is low-value, highly conditional and opportunistic and not in the best interests of Circor shareholders."

In a letter to shareholders, Circor said Crane's offer was "a change of tactics to attempt to take over your company, but it does not change the fact that it fails to deliver a compelling valuation for Circor."

"Circor is executing a detailed plan to deliver substantial earnings growth while deleveraring the company over the next 18 months," the letter said. "We are confident this plan will generate significant value for our shareholders in the near-term."

The letter said that "we expect our plan to deliver significant value to Circor shareholders over the next 18 months, far in excess of the offer."

Last week, industrial products maker Crane said it had begun a tender offer or $45 a share, or roughly $1.7 billion.

Crane had made a proposal in April, which the Burlington, Massachusetts-based Circor rejected last month.

"As expected, in response to our certain $45 per share offer," Crane said in a statement, "Circor today issued entirely new targets for 2020 that should be viewed skeptically in light of the company's long history of failing to achieve its own performance targets, which has led to chronic stock price underperformance. Even though Circor's new 2020 targets are lower than the targets they set in 2017, Circor's weak performance since 2017 suggests it also will likely miss the revised goals."

Circor were off nearly 1% to $45.50, while Crane dipped slightly to $80.40.