PICCs are made of two substances, either polyurethane or silicone, and are radiopaque measuring 50 to 60 cm in length with an outside diameter of 2 to 7 French (FR). The catheter may have a single- or double-lumen and can be open- or close-ended or valved. The particular device selected should be therapy specific, based on the number of lumens necessary for treatment, recognizing that the potential for infection increases with lumen number. The most common type of PICC line currently used is the 5-FR, double-lumen, closed-ended catheter.