[2] - Premium quality Low Profile chrome roller string trees For Strat, Tele and most similar design guitars - (see sizes at photo) 

Don't give up sustain to get smooth movement! Standard height roller string trees just aren't low enough to provide the needed  relief angle behind the nut for some strings resulting in loss of sustain.
Photo shows height compared to a standard roller string tree 1mm may not seem like much, but it can make a big difference.

• Increase tuning stability, decrease friction, drag and string wear.
• Keep your strings well seated in the nut while still allowing movement
• Designed to replace most stationary string trees (See sizes at picture)
• Package contains [2] roller string trees with [2] mounting screws
• Ships fast with first class delivery. Includes tracking!

Check out Charlies Gear for a lot more of the coolest gear on earth!
Wiring harnesses galore

These are from the same manufacturer as my full size string trees described below. Check out the feedback on them for unbiased comments about their quality!
"I put a set of these on my strat and I really love the way they work. They make a huge difference in friction. It makes a lot more sense too! The stock string trees that came with the guitar just scrape the string whenever it moves - but these are nice & smooth. I have had other roller trees in the past and these are by far the best quality yet"
Each part is checked and any that don't meet my standards go in the trash. Don't be fooled by some of the cheap string trees that are available. Most are either very low quality (look close) or you have to wait a month or more to get them from China - or both wait and get poor quality. **A great Lightnin Magic product**