BSODIAL(R) 58 styles Plastic Gears Cog Wheels All The Module 0.5 Robot Parts DIY Necessary ReviewbP PP SODIAL(R) 58 styles Plastic Gears Cog Wheels All The Module 0.5 Robot Parts DIY Necessary PA - Means tight Match(will small 0.05mm than standard)PB - Means loose Match(will larger 0.05mm than Standard)PGear Diameter : (Teeth +2) * modulus = Diameter of GearPModulus: 0.5PAperture 1.522.