Immobilising splint for the left hand. This splint has been designed in thermoplastic with a breathable interface to make recovery more comfortable to avoid sweating and discomfort that causes in the immobilized area. Its microhook closure can be trimmed to fit the length needed, helping to completely immobilize the metacarpophalangeal joints of the thumb whether in a post-surgical treatment or after a trauma, limiting the movements of flexion and extension, and radial and ulnar deviation to improve discomfort and injuries such as tendinitis, inflammation, instability, sports injuries, etc.. This size 1 wrist brace fits a circumference of less than 17 centimeters.