Helping an old lady down the road clean out her garage. She told me to keep anything I could use. Most of the stuff ( all old metal) I took to the scrap yard for her, but there was a tube of silver brazing flats.
050 x 1/8" by 15" long. What is it used for?

A lot depends on the silver content. It may be stamped on the rods. Sometimes used for higher strength joints on air conditioning copper tubing.

Probably BCuP-5, mostly for higher strength joints in HVAC. But, as suggested, look for anything stamped on the sticks. This might help: http://www.harrisproductsgroup.com/

The sticks say Harris 15 on them.
Might work for a temp fix on a skidder or tractor hyd. line?

Harris 15% is solder used for A/C systems, good results for materials with thermal expansion and vibration.

That is what we call silfoss in the HVAC industry (at least down here).We use it to solder the C/U line sets. It is quite expensive BTW.

So it's solder, not a brazing rod? Does it take a special flux?
Thankyou all, for the info guys.

No flux needed if you are sweating C/U,only a good heat on the above say about a stage above cherry but about the time you start to see the veridges pattern in the C/U.The C/U will suck the silfos to make a sealed joint.

Oh + another tip,start your flow at the side to bottom of the pipe;it will fill the void w/o dripping (+ lose some profit if you're in the business).It was always a chore to get the new kids to understand that there is no waste here.If you have a tiny bit of stick left,just sweat it to the next full stick so you have no scrap. No brainer right?....Right,thats why I work my shop alone these days;I've had it with kids that only want a paycheck but don't care about learning the trade.