I haven't been really impressed with it. It does three patterns, Mode 1 is slow alternating... but it's not a 50/50 flash, it flashes each side and there's a slight delay between them. Mode 2 is a faster wigwag.. it IS 50/50 and its almost too fast for halogen lights. Mode 3 is a combo of both 1 and 2 if I remember correctly. I never used that one.
The flasher works great to alternate LED lights if you just need a simple wig-wag on LED. For halogen lights, it leaves a lot to be desired. Also lacks the override for high beams.
But it's like... what... $20?