Thomas Medical TMI1156 Stylet for HS Catheter. HS Stiffening Stylet is 28cm and great for difficult cases. The Stylet is placed inside the HS Catheter and is used to provide added rigidity for a stenotic OS or to give the Catheter a memory for a retrograded or anteverted uterus. 10/BX. Priced per box. FREE Shipping!