what are these things?

[Canibul]

We bought an old boat, sailed it home, and have been taking stuff off of it. I am guessing that so far we've probably removed around 1200 lbs of stuff that previous owners had stored aboard that we dont feel we need to be on there. Television, microwave, washing machine, etc. And more. Lots more.

Today I was working in the rope locker, and I probably got rid of around 75 lbs of worn out line, non-stainless shackles, broken blocks, etc. Anyhow, some of the hardware on board is unfamiliar to me. Some of it is brand new, still with price tags on it. I am hoping someone here will recognize these bits and tell me what they're good for.

For example, I have several of these nifty little carabiner type things. But why?


And this other, stainless double pulley thing looks vaguely familiar, and I know i've seen one before, but cannot for the life of me remember what it does: