Dongker Optocoupler Isolation Board, 24V To 3.3V 8-Channel Photoelectric Product Details ?Appearance Size:85*98*18mm ?Adopt optocoupler. Limit Conversion Frequency:20KHz ?Applications:for signal isolation;MCUs and PLCs level conversion of signals;transform PNP,NPN singal into PNP signal;signal level voltage convert ?SHOP WITH CONFIDENCE: To Provide You With the Highest Quality Service, If You Have Any Question, Please Feel Free to Contact Us.We Will Provide After-sales Service Until You Are Satisfied. Payment We accept PayPal and credit cards via PayPal. Taxes - US We collect sales tax, as required by law. Shipping We make every effort of shipping within 3 business day of payment clearing. The estimated delivery time is 2 - 5 business days from the shipping date. Policies If you do need to return your item, please contact us via email (you will receive an email when your product ships with additional details - Subject: Important information about your purchase). You will then be provided with a return shipping label and packing slip. Pack the item carefully. Include the packing slip, apply the shipping label, and return the item within 30 business days of the date you request a return, or your return will be canceled. Once we receive your order we will inspect the return. Please allow up to 5 business days of receiving the returned item for your refund.