Simplifying the science of soil, the Active Air MGMP1 2-Way moisture and pH meter helps gardeners monitor the health and balance of their favorite plants. Great for use indoors or out, this piece does not require batteries for reliable use, season after season. Simply dip the meter into the soil and read moisture levels so you know when to water, pH levels so you know when to fertilize, and light levels so you know if you need to replace. Moisture readings register on a scale of 0 (dry) to 10 (moist). pH readings between pH 0 (acidic) and pH 10 (basic) are represented. Perfect plants don't get easier than this!