Check the listing for details. 1 PCs 1 Channel 5V Relay Module Board with Optocoupler Support High & Low Level. Condition: New. Listed at 4.99 USD. One, module Description:1, the module uses genuine quality relay, normally open interfaces Maximum load: AC 250V / 10A, DC 30V / 10A;2, using SMD optocoupler isolation, driving ability, stable performance; trigger current 5mA;3, the module voltage 5V4, the module can be set to trigger high or low with jumpers;5, fault-tolerant design, even if the control line is broken, the relay will not operate;6, the power indicator (green), relay state indicator (red)7, user-friendly interface design, all interfaces are available through the wiring terminal direct connection leads, very convenient8, module size: 50mm * 26mm * 18.5mm (L * W * H)9 with four mounting bolts holes, hole 3.1mm, 44.5mm * 20.5mm pitchTwo, module interface:1, DC +: positive power supply (2, DC-: negative one3, IN: can be high or low level control relayRelay outputs:1, NO: normally open relay interfaces, relay before hanging, pull back with COM2, COM: Relay Common Interface3, NC: normally closed relay interfaces, relay before with COM, pull vacant post High and low end of the trigger selection: 1. jumper LOW LOW trigger short-circuited; 2. When the trigger is high with high short jumper. - Many customers ask if they can ship their products in a paper envelope. Unfortunately, we cannot do that because merchandise needs extra protection, and USPS does not provide a tracking number for this type of service.- The shipping service we offer is First-Class Package Service, which is a domestic mail service offered by USPS. It is designed for mailing lightweight packages that weigh up to 15.99 ounces and offers delivery in 1-5 business days. It includes a tracking number, allowing customers to track their packages. USPS prices start at $4.75, but we don't have any control over shipping prices.