If you are looking for a lower cost instrument which qualifies as a near-reference monitor, please contact us about the ES-405. Because reference monitors are expensive and require shelters and limited locations around your state or country, the alternative is a near-reference monitor and lower cost, ease of deployment and maintenance, as well as reliability in comparison with reference type monitors. Reference type monitors used in the USA are predominantly the Met One Instruments BAM 1020. The BAM 1020 is also deployed around the world in over 130 countries. Please contact our sales department for more information and pricing at email@example.com or firstname.lastname@example.org.