The original LifeStraw was a Time Magazine Invention of the Year Winner. LifeStraw Steel is the company's "evolved" version, adding a 2-stage filtration system and more durable steel body to a 9" personal water filter that still removes a minimum of 99.9999% of waterborne bacteria from questionable sources as you slurp it.
A single LifeStraw Steel can filter up to 1,000 liters of water into potable refreshment without the use of chemicals, batteries, or even moving parts. This newer version also includes a replaceable activated carbon capsule that reduces chemical permeation (e.g., chlorine, pesticides, herbicides) for up to 100 liters per insert to produce better tasting, less smelly water.
LifeStraw Steel weighs a couple ounces more than the original--4.2 versus 2.0--but should prove to be more durable for long-term and long-trek use. It has a high flow rate (though it takes about 3 to 5 seconds for the first drops of water to travel through the filtration system), and is able to reduce water turbidity (cloudiness) and toxicity by staving off particles of approximately 0.2 microns, and slashing a minimum of 99.9%+ of protozoan parasites.