About this item Jacketed Double-Wall Design: inner reaction vessel with an annular jacket and integrated circulation ports for connection to external chillers/heaters; available in 250, 500 and 1000 ml Precise Thermal Control: jacket allows continuous circulation of thermal fluid for precise, stable temperature regulation during reactions Thickened, High-Clarity Glass: reinforced double-wall construction provides excellent transparency, corrosion resistance and elevated-temperature resilience for routine lab use Operational Versatility & Vacuum Rating: suitable for isothermal, atmospheric or reduced-pressure (vacuum) operations; maximum vacuum resistance: -0.06 MPa Pre-Use Preparation & Safety: rinse, thoroughly wash and dry the flask before use to ensure performance and safety; follow standard lab vacuum and thermal-handling procedures