Strong Magnetic Ring PK Magic Tricks Pro Magic Props There are 4 USA sizes 8,9,10 and 11 of the rings as below showed. 8 ---Inner Dia 18mm,inner circumference 56.5mm 9 ---Inner Dia 19mm, inner circumference 59.6mm 10---Inner dia 20mm, inner circumference 62.8mm and 11---Inner dia 21mm Package Includes: 1 x Magnetic Ring - Brand new and high quality strong magnetic ring - Can be use in numerous magic tricks,you can create your own magic - Material: Stainless Steel