CREATE TABLE table_51977 ("Nat." TEXT, "Name" TEXT, "Moving to" TEXT, "Type" TEXT, "Transfer window" TEXT, "Transfer fee" TEXT)

What is the transfer window with n/a as the Transfer fee, free agent for the Moving to, and Joe Sagar as the name?
SELECT "Transfer window" FROM table_51977 WHERE "Transfer fee" = 'n/a' AND "Moving to" = 'free agent' AND "Name" = 'joe sagar'
SELECT "Transfer window" FROM "table_51977" WHERE "Moving to" = 'free agent' AND "Name" = 'joe sagar' AND "Transfer fee" = 'n/a'