The primary winding is usally set up of one put-through conducting wire, which leads through the inner transformer opening. The secondary winding is buld-in. With the change of primary winding put-through number, you can change the conversion ratio and its current range.
The specification of linearity, current range and conversion slope is valid, when the secondary winding is loaded with the recommended resistor. If the linearity isn't the primary demand, it is possible to change the value of resisor corresponding the demand and thereby to obtain needed conversion slope or maximum current.