6% (20 volume) — the strength for conventional bleaching or for toning on naturally light (level 8 or above) blonde hair. Schwarzkopf BlondMe Premium Developer Oil Formula is a luxuriously caring professional developer specially formulated to work in harmony with BlondMe Toning and BlondMe Lightener. With a high concentration of nourishing mineral oil, BlondMe Developer supports the natural moisture balance of your clients' hair.