it comes with a sirf 3 chipset hence it is so sensitive, with the sirf III chipset gps receivers, you should expect a high degree of sensitivity as standard.  The chipset it uses is of a low power hence the battery is very small to accomodate the size.  Unfortunately the gpslim240 bluetooth gps receiver is not user replaceable as this is of a unique kind.  The run time is about 8 hours.

it has an on-off switch .  It also has three leds,an orange one that blinks when it has a fix, the blue one for bluetooth and red one that comes on when the battery power is slow.  It is chjarged by a standard mini usb connector. There is a tendency for the device to get dirty easily because of the shiny surface.
Note this has no socket for an external gps antennae but you wouldn’t miss it because of the sensitivity of the unit.

The device can also be used as a gps mouse but it will need a special usb cable to achieve this. Like I said earlier on performance is as what has come to be expected of sirf 3 gps receivers, It picks up satellite signals right from the middle of my living room.

In summary this is an excellent compact bluetooth gps receiver, suited for someone who is fashion conscious, the only downside forme is that the battery is not user replaceable but I guess I can’t eat my cake and have it. You can get a cheap on here

Car Charger for Holux BT-321 GR-230 231 236 240 GPSlim £0.99 Auction Ends: Thursday Feb-23-2012 14:52:13 GMT   | Watch this Item

Looking at the holux gpslim236, It has three lights on the top, a red one that flashes to indicate a gps fix, a blue one for bluetooth and the third yellowish light that signals low battery warning.  it has an on-off switch on the side as well as a socket for an external antennae , something I doubt you will ever need due to the sensitivity of the gps receiver. It also comes with a removeable 850mAh rechargeable lithium-ion battery that provides up to 10 hours working operation.

Something worth mentioning is that the holux gpslim 236 can also be used as a wired gps mouse for non bluetooth pda devices but you will need a special optional usb cable.In otherwords it is a 2 in 1 device. It is charged using a standard mini usb cable.  the package inludes a cigarette car charger as well as an ac charger. The only downside is that if you need to use it as a wired mouse then you have to purchase an optional usb cable specifically for that, I guess I am asking too much if I expected to provide such a cable as standard

The cheapest place I found to get this receiver is on Ebay

GPS Antenna for Holux Bluetooth GR 239, GPSlim 236 New £7.52 Auction Ends: Sunday Feb-05-2012 4:01:31 GMT   | Watch this Item

Battery for Holux GPSlim236 GR236 M1000 M1000B M1000C HXE-W01 3.7V 1000mAh £9.99 Auction Ends: Monday Feb-06-2012 9:56:29 GMT   | Watch this Item

Holux data cable for GPSlim236/M-1000 Series as G-Mouse £6.32 Auction Ends: Tuesday Feb-07-2012 16:35:18 GMT   | Watch this Item

1000mAh Battery For Holux GPSlim236, GR236, M1000 HXE-W01, BA-01 £10.97 Auction Ends: Saturday Feb-11-2012 14:09:00 GMT   | Watch this Item

BATTERY FOR Holux GPSlim236,GR236,M1000,i-Trek M1,M6,M7 £9.40 Auction Ends: Sunday Feb-12-2012 13:30:05 GMT   | Watch this Item

Battery for Holux GPSlim236 / M-1000 Series M 1000 B C £6.32 Auction Ends: Sunday Feb-12-2012 13:33:53 GMT   | Watch this Item

The bt77 uses a nemerix chipset, it is a 16 channel GPS tracking up to 16 satellites. Once fully charged it can last up to 30 hours. The box contents include the gps receiver and battery, an ac charger , usb car charger , a usb cable  and a cd. It may also come with a dashboard mat to place the receiver on so t doesn’t slide around. Because it comes with a usb cable , it can also be charged from a pc.

The device itself measures 81mm by 44mm by 20 mm. It has 2 flashing lights, a blue and red one,  the red light flashes when it has locked on to enough satellites otherwise it is steady. The blue one has to do with Bluetooth functionality.

With regards to performance, this isn’t a sirf 3 gps receiver but it comes close. The initial time to fix is less than 5 minutes, after that it takes 1-2 minutes and in most cases less than a minutes to acquire satellites.  I made comparisons between this and a sirf 3 gps receiver and this picked up 3 satellites in the middle of my living room while the sirf 3 one was fluctuating between 3 and 4.  Outside it was locking on to 5 to 8 satellites and it worked effortlessly from the car glove compartment.

The bt77  is an exceptional value for me because it is now very cheap considering it’s performance. It can be bought of ebay for less than £50 including postage.  It is really worth checking out.

Snooper S900 Truckmate Lite HGV Lorry GPS Sat Nav EU £239.99 Auction Ends: Saturday Feb-04-2012 8:26:45 GMT   | Watch this Item

VW PASSAT MK6 W8 GPS SAT NAV TMC CANBUS BOX 3B2 919 894 £49.99 (0 Bid) Auction Ends: Saturday Feb-04-2012 9:27:23 GMT   | Watch this Item

(UK Stock) 4GB 5.0 inch Car GPS Receiver Navigation Sat Nav New UK/EU Maps 2D/3D £44.99 Auction Ends: Saturday Feb-04-2012 9:35:11 GMT   | Watch this Item

Snooper S900 Ventura Caravan and Motorhome GPS Sat Nav European Maps NEW £249.99 Auction Ends: Saturday Feb-04-2012 9:54:48 GMT   | Watch this Item

Binatone G350 Automotive GPS Receiver SAT NAV USED BUT EXCELLENT CONDITION £22.00 (12 Bids) Auction Ends: Saturday Feb-04-2012 10:06:08 GMT   | Watch this Item

HOT! 4.3" 4.3 GPS SAT NAV FM MP3/4 FREE MAP 2GB BLUE £26.00 (5 Bids) Auction Ends: Saturday Feb-04-2012 10:18:41 GMT   | Watch this Item