Kleinblatt is closed on those holidays (2021):

    1st  of January New Year’s Day
 26th  of March till 4th of April Pessah (jewish easter)
 17th   of May and 18th of May  Shavouoth (jewish pentecost)
 24th  of July till 15th of August yearly holidays
    7th  of September till 8th September Rosh hashana (jewish newyear)
  16th  of September Yom kippoer (day of reconciliation)
  21st  of September till 22nd of  September Soekoth (feast of tabernacles)
  28th of September till 29th of September Simchat torah (feast of the bible)