Magnetic clasp -stainless steel. Really strong - fits into tube, so cannot slide sideways and needs to be pulled open. Until you have glued something in to pull on, you will probably need pliers to pull the two halves apart. Nice deep cavities. Securely glue onto leather, cord, silversilk, viking knit, or kumihimo, beaded rope (to resist the pulling action of opening.)
Made in China. 19mm Hole size is approx. ID 5mm. By the each.