Has anyone ever used these and do they work or not?

I use the Crystal and prefer it over braid.

I use the microfuse because it is fluorescent. I like it alot of people don't but it beats changing line all the time. I night fish about 50% of the time in the summer so it works well for me.  

I've not used the Crystal myself, but I know several people who have used it for leader material on their tip-ups.  

Every single person said they would never use it for that application again.  The line is advertised as being almost as clear as mono, but it shows up as a milky white color in the water.

The line is advertised as being almost as clear as mono, but it shows up as a milky white color in the water.

And out of the water.  I can certainly confirm it is NOT clear as mono.

Alright guys, I'll just pass on it.

Wait, what?  Give it a shot, you might like it.  I recommend it highly, I'm just saying it's not clear as mono.

Try the Microfuse. It's got a grayish blue tint to it

and is less visible than Crystal. I've been using it

for over a year and really like it.

imo fireline isnt what it used to be..i hate that stuff now nothing but problems and money down the tubes.