For Hydro/Temp display (ambient) for comparison to dryer display.  I got these from Amazon https://www.amazon.com/gp/product/B09TY3WHDR/ref=ox_sc_act_title_1?smid=AFMRW02PTHTEX&psc=1 .  They fit both this holder and the supplied OEM desiccant container.   I wanted the hydro and temp displayed in the clear OEM desiccant holder then I made this for ambient (room) comparison.  They both fit snug but are removeable with a good push of both thumbs to change batteries.