'For the electronics industry, the television is an important but increasingly difficult product to sell." Before elaborating on the grammatical function of 'but' in this sentence, it is neccessary to correct a prior error which inevitably affects it. "For the electronics industry, the television is : 1) an important -product- 2)increasingly difficult product to sell. While it's okay to say "the television is an important product for the electronics industry", to say "the television is an increasingly difficult product to sell for the electronics industry", on the other hand, doesn't make sense. 'But' splits the noun "Product" into the above-two attributes. However, a confusing double-reference to 'the electronic industry" was made as well. References stick to 'for' like a magnet. Although the two ideas are clearly highlighted, the sentence to flow needs to be entirely rewritten I'm afraid. Also, 'but'+'and'= yet. I propose: Television is an important product of the Electronic industry YET increasingly difficult to sell ( We haven't have had any ' easy ' sales on television yet).