The unique Thermo Scientific® Orion Sure-Flow® Junction is a free-flowing liquid-to-liquid junction assures you of the most stable, drift-free measurements. The easy-to-clean junctions never clog-simply press the cap and flush the junction area. Release the cap and the junction is reset. Now even the most problematic, dirty or viscous samples can be easily measured without a clogged junction! Same ROSS™ features as PH4200. Detachable bulb guard is included with PH4205-1BN thru -3BN.