2 3/4x 3 3/4" Fan Kenzans, K-121 From Hollow Creek Bonsai 2 3/4x 3 3/4" Black Fan Kenzans, K-121 From www.hollowcreekbonsai.com . Known by many different names Pin Frog, Flower Frog, Flower Spikes, Needle Holder and Kenzan it is a must for flower arranging enthusiasts. Flower frogs are reusable pieces of lead with small spikes that hold flowers in place within the arrangement.