A skin brush head for use with a motorized personal appliance, comprising: a body having an outer surface; a treatment applicator extending from the outer surface of the body, wherein the treatment applicator is configured to apply treatment to a subject's skin; and a replacement indicator, characterized in that the replacement indicator (180, 380, 480, 580, 680, 780, 880, 980) includes an indicator member (186, 386, 486, 586, 686, 786, 886, 986) movable with respect to the body, a biasing member (188, 388, 488, 588, 688, 788, 888, 988), and a retainer (182, 392, 492, 592, 692, 46, 892, 982), wherein the indicator member (186, 386, 486, 586, 686, 786, 886, 986) is configured to be moved to a stowed position against a biasing force of the biasing member (188, 388, 488, 588, 688, 788, 888, 988) and restrained in the stowed position via contact with the retainer (182, 392, 492, 592, 692, 46, 892, 982), and is configured to move to a replacement position in the direction of the treatment applicator after an amount of usage of the skin brush head has occurred, wherein the replacement position is located outwardly of the outer surface of the body and indicates to a user a recommendation for replacement of the skin brush head, wherein the replacement indicator (180, 380, 480, 580, 680, 780, 880, 980) is configured to trigger the release of the indicator member (186, 386, 486, 586, 686, 786, 886, 986) and allow the indicator member (186, 386, 486, 586, 686, 786, 886, 986) to transition from the stowed position to the replacement position under the biasing force of the biasing member (188, 388, 488, 588, 688, 788, 888, 988) based on oxidation. a body having an outer surface; a treatment applicator extending from the outer surface of the body, wherein the treatment applicator is configured to apply treatment to a subject's skin; and a replacement indicator, characterized in that the replacement indicator (180, 380, 480, 580, 680, 780, 880, 980) includes an indicator member (186, 386, 486, 586, 686, 786, 886, 986) movable with respect to the body, a biasing member (188, 388, 488, 588, 688, 788, 888, 988), and a retainer (182, 392, 492, 592, 692, 46, 892, 982), wherein the indicator member (186, 386, 486, 586, 686, 786, 886, 986) is configured to be moved to a stowed position against a biasing force of the biasing member (188, 388, 488, 588, 688, 788, 888, 988) and restrained in the stowed position via contact with the retainer (182, 392, 492, 592, 692, 46, 892, 982), and is configured to move to a replacement position in the direction of the treatment applicator after an amount of usage of the skin brush head has occurred, wherein the replacement position is located outwardly of the outer surface of the body and indicates to a user a recommendation for replacement of the skin brush head, wherein the replacement indicator (180, 380, 480, 580, 680, 780, 880, 980) is configured to trigger the release of the indicator member (186, 386, 486, 586, 686, 786, 886, 986) and allow the indicator member (186, 386, 486, 586, 686, 786, 886, 986) to transition from the stowed position to the replacement position under the biasing force of the biasing member (188, 388, 488, 588, 688, 788, 888, 988) based on oxidation.