The Norway international completed his move yesterday.
His former Eredivisie club said in a statement: "SC Heerenveen regrets the departure of Magnus Eikrem after six months, but the Norwegian was recently given permission to go for contract. talks with Cardiff City.
"Magnus had previously indicated to the club that he would rather go for his career.
"The financial aspect is also currently also very important to the club. and that has certainly played a role in the decision to allow Eikrem a transfer.
"Magnus Eikrem at Heerenveen was a model professional, both on and outside the field.
"The club also wishes him every success in the remainder of his career at Cardiff."
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