The Proton T-4 produces a bi-directional field which provides a 20,000 Gauss positive field and a 20,000 Gauss Negative field. The T-4 achieves this by using a unique, patented “Reverse Polarity”. Other degaussers may have either a positive or negative pulse, but only one. The T-4 has both and it is fully automatic. This ensures complete and permanent erasure of your data and will protect your sensitive information for years to come.