Bottle Mount Vaccinator Replacement Barrel with O-Ring, Durable, impact-resistant plastic syringe provides a quick bottle changing system that fits most 100 ml bottles. Fast-Fit system protects glass bottles against breakage. Steel needle nib adds great strength to a critical stress point. Ergonomical handle design offers easier, more comfortable use. 0.5 cc dosage adjustable from 1/10-1/2 cc; 2 cc dosage adjustable from 1/4-2 cc; 5 cc dosage adjustable from 1/2-5 cc.