The whole range of color and printed/non-printed ID Tags is made of aluminum and it is safe to use for IVF and other cryo applications. Our prints on tags are durable and permanent, unlike hand writing on plain tags, with permanent cryo marker pens. This feature makes our tags the safest choice for storage inside LN2 tanks. Our standard print on tags is the number from 1 to 35 but we can make customised prints on tags. Please ask us the minimum purchase order quantity required for customized prints on tags.