Traditional neck catheters are made of Teflon and can cause blood clots or cracking if left in place for more than 48 hours. This large polyurethane catheter over the needle allows the catheter to remain in place for up to 30 days. EQUIVET HiFlow LongTerm (HFLT) intravenous catheters soften at body temperature. Some common problems associated with catheters, such as phlebitis, can be reduced by using these polyurethane catheters. Non-thrombogenic and non-cracking. They can be safely left in the vein for up to 30 days. Suture wings with holes.