Excellent Visibility, brighter than the rest.  The shock resistant LED never needs replacing.  These floats are powered by two 1.5 volt button cell batteries (LR44).  Batteries are included with each Night Bobby.  The unique Line-Lock line attachment allows doe use as a slip or fixed position float.  Float can be removed without cutting line, removing bait, hook or sinker.  Measures 1.85 inches across.