Features: Wireless Explainer - Transmitter, mainly through the equipment to pass voice content, and the receiver in the same - channel can be realized by one person to explain, more people listen. 2.4G frequency, highly confidentiality, 35 Channel. Channel number, signal and other basic information are displayed through theOLD screen. Matching key and knob make the product easy to operate and beautiful. 2.4G international common frequency; Transmission is far, 100~150meters without obstacle.Wireless Explainer-Receiver, mainly used to receive voice content transmitted by transmitter,2.4G frequency, strong antiinterference ability Support more scene, guided corporate reception, wireless conference, factory explanation, wireless teaching and other large-scale scene. Specifications: Product Model:YWI21-T Transmitter/Receiver（Optional） Distance: 100~150m barrierfree distance Number of Channel: 35 Frequency: 2.4GHz Battery capacity: 1000mAh Charging Interface: DC5V1A (TypeC) Product Color: White Material: ABS + display Product weight: 62.20g Product size: about 130x50x25mm/5.12x1.97x0.98in Receiver: 2.4G international common frequency bands; Long transmission distanced, 100-150meters barrierfree distances; Operating temperature: 55℃~125 Distances: 100~150m barrierfree Number of Channel: 35 Frequency: 2.4GHz Battery capacity: 1000mAh Charging Interface: DC5V1A (TypeC) Material: ABS + display Receiver size: about 81x45x19mm/3.19x1.77x0.75in Weight: 42.0g Package Includes: Transmitter Accessories: Transmitter x1 Ear mark x1 Lanyardx1 TypeC charging cable x1 Chinese English manual x1 Receiver Accessories:（Optional） Receiver x1 Earphone x1 Lanyardx1 TypeC charging cable x1 Chinese English manual x1 note: Due to the problem of lighting effects and shooting there might be tolerances in the product, please understand. Please allow 0-2mm error due to manual measurment.