for  DELL 11z 1545 XT2 E4300 E4200 you need a dell 365 bluetooth module(without cable)

Dell Wireless 365 Bluetooth (Kit) (555-11600)

Overview
The Wireless 365 Bluetooth Card from Dell is designed to provide high performance and an efficient Bluetooth solution for portable devices. It reduces the power consumption and increases the battery life by use of Sniff Sub-Rate (SSR) that lowers the number of times the Bluetooth device is queried. Also the Simple Secure Pairing (SSP) improves the pairing experience for Bluetooth devices, while increasing the use and strength of security. Features like Encryption Pause Resume enables an encryption key to be refreshed, for stronger encryption and longer connections hours. It provides more information during the inquiry procedure to allow better filtering of devices before connection by using Extended Inquiry Response. This product has been tested and validated on Dell systems. It is supported by Dell Technical Support when used with a Dell system.

Compatible With:
11z 1545 XT2 E4300 E4200

Wireless : Dell Wireless 365 Bluetooth (Kit) (555-11600)
Manufacturer Part : 555-11600
Dell Part : 555-11600
 
The price is 20usd on ebay.

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