PurGro GroBot pH Probe, Industrial Replacement meters-&-solutions these fans are engineered to

these fans are engineered to produce greater air movement and superior cooling no matter the application

The 24" Expander is made of highly reflective material and can be adjusted to 4 different positions

The porous structure has a high water capacity and is suitable for both ebb/flood and top irrigation systems

during winter months

PurGro GroBot pH Probe, Industrial Replacement meters-&-solutions these fans are engineered toThese don't look like the ones from the hydro store because they are double junction, flat surface pH probes typically used in chemical plants for process control. They last longer, stay cleaner and are built to mount in line inside your GroBot Evolution. Cost a few bucks more, but these are the good ones. Proudly made in the USA.