As the former head of the SRDI, Urahara has immense knowledge and understanding of the flow, application, and consistency of spiritual energy.[114] He knows how to break barriers of the spiritually superior noble clans, a feat which even captains cannot achieve.[177] He can silently, and without warning, use low and mid-level Kidō to great effect.[178][179][180] He can rapidly use a single high-level Kidō repeatedly, or multiple ones in quick succession, by name alone, without incantation or calling the type and level, while retaining considerable power and control.[181][117] He is highly proficient in healing Kidō.[182] He can use level 99 Kidō,[115] but has more difficulty with Kidō above level 88 without incantation,[116] as he had to use the incantation to ensure enough power for a level 91 Kidō. He can use multiple Kidō in conjunction for various combination and diversion tactics, and have them remain undetected until sprung in sync in a chain reaction. Urahara can create his own unique high-level Kidō.[183] Aizen admitted that if not for the Hōgyoku, Urahara's prowess would have surely defeated him.[