1 1/2” x 1” open cat pin. J4504p. Not sure if these are hypoallergenic. Christine Alexander only used Swarovski crystals and elements on their clothing. I am 80% sure that was also true for their jewelry but may just be good quality rhinestones. unfortunately I cannot ask them as they have gone out of business. Jewelry is new, never worn or displayed. purchased from Christine before they closed for my online store. All measurements are approximates but as close as I could get