Low viscosity, unaccelerated, self-extinguishing, medium reactivity halogenated unsaturated polyester resin for use in hand lay-up systems. Fully cured laminates made from DION® FR 7721-03 NP reinforced with glass fibre can obtain a Class M2 according to NF P92 501 and Class F2 according to NF F16 101, at 20 – 25% glass content. DION® FR 7721-03 NP is a specially formulated filled resin system to give excellent fire retardant properties.