These precision BBs are designed to glow when used with a tracer unit and are made to a high standard for consistent performance.
 
Product Specifications
According to various retailers and the manufacturer Nuprol, here are the key specifications for the 
Nuprol RZR BIO-BB tracer green 3500 rounds 0.20g
: 
Weight: 0.20g per BB. This weight is often used by airsoft sites to chrono an AEG's (Automatic Electric Gun) power level.
Quantity: Approximately 3500 rounds per bottle.
Type: Biodegradable green tracer BBs. They are designed to glow in the dark when used with an airsoft tracer unit.
Diameter & Tolerance: Sub-Six 5.95 mm diameter with a low tolerance of +/- 0.01 mm, which makes them suitable for high-performance and "tightbore" (<6.03mm) inner barrels.
Finish: Triple polished for enhanced flight performance and reduced feeding issues.
Quality: Manufactured in Taiwan with ISO quality accreditations, undergoing multiple quality control checks.
Environmental Standard: The bio-options meet the internationally recognised ISO standard for Controlled Aerobic Compositing – DIN EN 13432:2000 | ISO 14855-1:2012.