When sourcing outdoor speakers, the most critical factor is the IP (Ingress Protection) Rating. For general outdoor use, a minimum of IP44 is required, but for areas exposed to heavy rain or poolside splashes, IP65 or IP66 is highly recommended to ensure dust-tightness and protection against powerful water jets. Additionally, evaluate the UV-resistance of the housing material (typically ABS or high-density polypropylene) to prevent cracking and discoloration under direct sunlight. For audio performance, prioritize speakers with a frequency response of 60Hz-20kHz and a sensitivity of at least 88dB to ensure clear sound projection in open-air environments.