Profile: Holroyd Instruments Ltd. specializes in acoustic emission sensors and systems. Our product line includes MHC-memo Pro, MHC-memo lite, MHC-classic plus, R&D sensors, MHC-classic and MHC-solo. Our MHC-airborne sensor is an accessory for the MHC range of portable instruments that enables users to detect leaks with air or vacuum systems. Our AE sensor types are available for permanent installation equally suited to use for either continuous monitoring or temporary attachment applications. Our AE sensor types are available for permanent installation equally suited to use for either continuous monitoring or temporary attachment applications.