AST 550 is a fully-automatic cryostat microtome whose specimen forward and backward movement are controlled by motor . So it can get high quality section and easily operated . ? It is designed under overall engineering and ergonomic concept. All the components are processed by computer numerical controlled machine. ? Retraction function prevents specimen damage from blade . ? Total thickness calculation . ? The low temperature refrigeration system with environment friendly refrigerant R404. ? Adopt UV and O3 sterilize for 30 minutes every time. ? Peltier specimen clamp refrigeration may be turned on or off manually. ? Two defrosting methods: manual and automatic. ? Two running ways : manual and automatic. ? Emergency stop function : Press the red button to stop running when any emergency happens. ? The high precision unit is enclosed outside the cryostat chamber to prevent it from thermal expansion and contraction , and keep minimum maintenance requirement . ? Artificial intelligent interface is easy for user to learn and operate. ? LCD screen can display all information including thickness, thickness sum , controlling time, temperature, timed on/off and so on. ? Sleep Function. After activating this function, the temperature in cryostat chamber can be kept between -1? and - 10?; After stopping this function, the temperature in freeze chamber will arrive to working temperature within 30 minutes. ? Control panel with locking function could avoid wrong operation. ? Handwheel locking function. ? Wide freezing shelf load 8 specimen cassettes simultaneously ,and two of them are equipped with peltier to meet different temperature .