Palm Defender Insert3 Grams Three Half Second Bursts Effective Range Three Feet Unlike common throwaway aerosol can defense products, ASP Defenders are highly engineered dispersion devices that use a proprietary, replaceable OC (Oleoresin Capsicum) Insert. These Inserts are precision machined from aerospace aluminum and solid brass, and incorporate a specially produced valve system and patented dispensing mechanism. The entire unit is O ring sealed.