CREATE TABLE table_18815 ("Specification" TEXT, "Gender" TEXT, "Junior High School  ( 12\\u201315 yrs ) " TEXT, "Senior High School  ( 15\\u201318 yrs ) " TEXT, "University students and Adults  ( 18yrs+ ) " TEXT)

What is the gender of senior high school 26mm?
SELECT "Gender" FROM table_18815 WHERE "Senior High School (15\u201318 yrs)" = '26mm'
SELECT "Gender" FROM "table_18815" WHERE "Senior High School (15\u201318 yrs)" = '26mm'