The most widely used surveillance/earpiece kits for the CP and CT series are pieces that can work and be shared with multiple users. Those earpieces are the PMLN4443, PMLN5001, PMLN5807, PMLN6531, PMLN6532, HKLN4604 and HKLN4424. These units also come with a 1 year warranty. 
If your looking to step up to a more expensive individual personal earpiece, look no further than the RLN5318, PMLN6445, PMLN6530 and PMLN6536. These units have the type of ear piece that is inserted into your ear opening which makes this a more personal use earpiece used more with security and surveillance scenarios. These units are typically more expensive but the PTT and sound quality are better.
The is such a wide range of earpieces that can be used for the CP and CT series radios that we will try to mention without boring you completely. Let’s look at the PMLN4443, this unit features and in-line PTT with VOX. This VOX feature allows the user to be hands free and communicate with other workers without having to remove their hands from critical applications that require control. The downside is as soon as you start speaking everyone hears the conversation. This PMLN4443 with VOX feature is easily disabled by the switch control on the PTT. The PMLN6531 is one of the newer models with the same style we call Ear Hanger and also comes with VOX.
VOX technology only works when you have the earpiece and radio that are both capable of VOX operations. Not all radios are able to operate in VOX mode. VOX has been used in Industrial and Commercial lines of work where the user is very hands on and any removal of hands from sensitive controls could put someone at risk. VOX is used widely with Crane and Heavy Equipment Operators.
Another good earpiece is the D Style PMLN5001 with Micro/Mini PTT. The PMLN5001 D Style is describing the actual look of the part that goes over the ear. It has the speaker built into the D section that lies over the ear and easy to clean for multiple users. This type of earpiece is commonly found in use with drive through fast food and restaurants.
Another favorite is the PMLN6532 which is the C Style which is easy for day long wear and usually doesn’t create ear fatigue. The PMLN6532 comes with a swivel earpiece allowing for use with either ear, in-line PTT and clothing clip. This PMLN6532 has heavy use in the retail and restaurant business sector.
There is a new comer to the earpiece market, which is a Snap Lock. The Snap Lock Earpiece is designed for the changeability of different earpiece styles while keeping the PTT and Connector to the radio the same. The different snap on earpieces is the Acoustical Tube, D-Style, C-Style, Ear Hanger and Ear Bud. Which ever is your comfort style this option makes it less expensive to switch out one style with another without breaking the bank. This Snap Lock system also allows business owners the ability to provide individual earpiece’s to employees without the worry transferring any cross contamination.
A great listen only earpiece we can’t leave out is the RLN4941 which is used in conjunction with the PMMN4013 speaker mic. The RLN4941 is a listen only and has a 3.5mm right angle plug and is used to keep conversation discreet during transmission. In very noisy environments it is too difficult to hear transmissions over the radio or speaker mic if your not using the RLN4941.
These 2 prong earpiece’s will work with any Motorola 2 prong accessory port. Below is a list of compatible radios. (Not All Radios Mentioned)
BPR20, BPR40, CP040, CP080, CP100, CP110, CP120, CP125, CP140, CP150, CP1600, CP1660, CP185, CP200, CP200d, CP200XLS, CP220, CP240, CP250, CP300, CP476, CP477, CLS1110, CLS1410, CT150, CT250, CT450, CT450LS, GP300, LTS2000, P1225, PR400, RDU, RDV, RMU, RMV, VL130, VL50, XU, XV, and many others