Noctua nf a15 pwm round frame premium pwm fan the fully featured nf a15 pwm features 120mm mounting holes and has been enlarged to 150mm width in order to provide superior performance on todays high end cpu coolers the nf a15 is a premium quality quiet 140mm fan with a round frame that complies with noctuas aao advanced acoustic optimisation standard the nf a15s frame features 120mm mounting holes 105mm spacing and has been enlarged to 150mm width in order to provide superior performa