Some Techie

The gear ratio is largest for reverse and hence, it requires more RPM from engine to drive it. If low RPM, or accelerater is pressed lightly, it won't be able to drive properly. Hence, it vibrates.

OS Android RAM 4 GB Item Weight 168 g Product Dimensions 15.8 x 0.8 x 7.5 cm Batteries: 1 Lithium ion batteries required. (included) Item model number Nova 3i Wireless communication technologies Bluetooth;WiFi Hotspot Connectivity technologies GSM;(B2/B3/B5/B8);3G;WCDMA;(B1/B5/B8);4G LTE;TD;(B38,B40,B41);FDD;(B1/B3/B5/B7/B8) Special features Dual SIM;GPS;Music Player;Video Player;E-mail Other camera features 24MP + 2MP Form factor Touchscreen Phone Weight 168 Grams Colour Black Battery Power Rating 3340 Whats in the box Handset, Charger, Micro USB Cable, QSG, Warranty Card, Eject Tool, TPU Protective Case and TP Protectice Fil