What is a Mallet Finger/Thumb Splint? 

A mallet finger/thumb splint is designed to immobilise the end of a finger or thumb to keep the bone straight and prevent against any further injury. 

They are often put on the digit, then taped on to stop them moving around. This still allows the finger or thumb to breath while providing a rigid support.

Use a 1.25cm Zinc Oxide (rigid, sticky tape), 2.5cm Tear Lite (stretchy, sticky tape) or 2.5cm Cohesive (stretchy, rubberised grip tape but not "sticky") for securing.

Measure the circumference of the top knuckle of your finger or thumb, at the widest point.