This is the "Bar Braid Pin" by Hector Aguilar
featured on page 150 of the book SILVER MASTERS OF MEXICO by Penny C. Morrill. She dates it circa 1940 and it is in 940 silver.
Measuring 2 7/8" by 1/2", it weighs 13 grams and is in fine original condition. Signed as shown. One of his very famous designs.