The Electro-Voice Sx300PI Speaker System is a weather-resistant version of the Sx300 . Weather resistance is increased through its foam backed, full-face stainless steel grill. Additionally, there are two port-plugs included for user install when increased weather resistance is necessary.

The speaker and crossover network are designed to achieve Constant-Directivity.  A feature of the Sx Series, Contant-Directivity helps eliminate "hot spots" and gives better, more balanced coverage to areas traditionally weak in coverage. An additional benefit of the Sx300PI coverage pattern is its increased avoidance of early reflections which can degrade overall performance.

Acoustical and mechanical ring modes are controlled using RMD (Ring-Mode Decoupling) allowing more intelligibility and less resonance, giving the listener less "muddiness".

Circuit protection is provided for the molded-in, pure titanium horn driver reducing the input by 6dB if the nominal rating is passed. With a durable, damage resistant structural foam enclosure, two molded-in handles, and multiple suspension points, the Sx300PI works well as either a portable or suspended system and the enclosure design allows for multiple speakers to be combined to create an array system.