Choose from 10 different Indigo® pH & litmus strips, papers & sheets for all your acid & alkaline testing requirements at home or in the lab. Full documentation provided including a Stability Statement, Certificate of Analysis & SDS available on-line. Optional next day delivery in any quantity of most items.Buy Indigo® test strips, the brand you can trust for accuracy & technical support. Call us on our toll free line for immediate assistance or e-mail us with your questions. 1 hour response is typical during business hours, M-F, slightly longer on weekends.