Kleinblatt is closed on those holidays (2021):

January 1st	New Years Day
March 27th to April 4th	Pessah (jewish easter)
May 17th  to May 18th	Shavouoth (jewish pentecost)
July 24th to August 15th	yearly holidays
September 7th till September 8th	Rosh hashana (jewish newyear)
September 16th	Yom kippoer (day of reconciliation)
September 21st to September 22nd	Soekoth (feast of tabernacles)
September 28th to September 29th	Simchat torah (feast of the bible)