Electron Energy has successfully developed a new grade of zero Reversible Temperture Coeffeicient (RTC) magnets with maximum energy product, (BH) max , of 18.0 MGOe and H k ≫ 12 kOe. The new grade of zero RTC 18 augments the existing product line and surpasses the prior highest energy zero RTC grade with a (BH)max of 16 MGOe. The RTC of the newly developed magnets is suitable for TWT applications where little change in magnetic induction, B r , over a wide temperature range of up to −50° to +150° C is desired. Excellent magnetic properties were obtained with reversible temperature coefficients on the order of − 0.001 % /° C .