Honeywell on Friday reached out to United Technologies shareholders on its bid to merge the two companies, saying the "compelling nature of a combination is undeniable."
The companies said earlier this week that they had held merger talks but did not provide any deal details at the time.
Honeywell has proposed a cash and stock deal for United Technologies at $108 a share.
Under the deal, United Tech shareholders would get $42.63 in cash, plus 0.614 Honeywell shares. United Tech shareholders would own 40 percent of the company.