How to make box collider same size as gameobject

I am creating a gameobject from from an .obj exported from blender and now I want to add a box collider to this object in order to be able to click on it but I am having trouble making it the same size. Currently I am using the gameobjects scale to set the size but this does not seem to be the right way of doing things as it makes my boxcollider a cube. This is the code I currently have to create my gameobject and collider where humanPriest is a reference to my object that I imported from blender.

 Card card = new Card(0);
 card.cardObject = (GameObject) GameObject.Instantiate(humanPriest,new Vector3(Camera.current.transform.position.x,Camera.current.transform.position.y-25.0f,Camera.current.transform.position.z+10.0f),Quaternion.Euler(new Vector3(5.0f, 0.0f, 0.0f)));
 card.boxCollider = (BoxCollider) card.cardObject.AddComponent<BoxCollider>();

Then I try to change the size of the boxcollider like so.

 foreach (Card c in userDeck) {
     c.cardObject.GetComponent<BoxCollider>().size = c.cardObject.transform.localScale;
 }

How can I get the actual size of my gameobject and set the boxcollider to the same size?