IMPULSE The Princeton Tec Impulse LED Light incorporates the best features of its Pulsar line of mini-flashlights and takes it to the next level. Fully waterproof, this tiny light features an electronic switching system with five settings (low, medium, high, slow strobe, fast strobe) for its LED bulb. The switch also has an automatic shut off feature. Buy plenty -- you"ll want one for every keying, ball cap, backpack and book bag in your arsenal!