The One Systems SP.PMK is designed for mounting ONE.SP speakers on either round or square poles. For square poles, the minimum flat dimension must be 3.75 inches (95.25 mm) at the speaker's mounting height and for round poles, the minimum required diameter is 4 inches (101.6 mm) at the speaker's mounting height. Installation of the SP.PMK requires Band-It stainless steel banding and buckles (not supplied by or available through One Systems). For safety reasons, it is critical that the mounting pole be capable of supporting the combined load of the loudspeaker, the SP.PMK bracket, all suspension hardware as well as providing the proper safety factors. Please consult the SP.PMK's Installation Guide for more details. The SP.PMK, when installed correctly, provides a safe, solid, cost-effective attachment for One Systems ONE.SP loudspeakers for installation on poles.