English to Spanish Medical Medical: Health Care piel

en un texto que habla sobre las normas de la FDA respecto a los bloqueadores aparece lo siguiente:

A recent development in sunscreen regulation is the advent of a broad-spectrum test that the FDA considers to have sufficient supporting data to establish a sunscreen’s ability to protect also against UVA. This is known as the critical wavelength (CW) and the criteria for labeling a product as “broad spectrum” is a CW ≥370 nm.1,3,4 This is because evidence suggests that UV radiation in the range of 290-370 nm is responsible for most of the harm caused by solar exposure.4 Products with a CW ≥370 nm plus an SPF value that designates the magnitude of overall protective ability may be advertised with the claim “broad spectrum SPF”.3

no se como poner "that designates the magnitude of overall protective ability" literalmente no tiene sentido para, yo lo entiendo como "... y un factor de protección con una capacidad de protección general elevada"...en internet he encontrado que deben ser de más de 15 .....la frase "that designates the magnitude" la verdad me parece muy complicada de entender

gracias por su ayuda es urgente