The part number is A9638053 I believe. I have the Oxford cruiser grips on mine and they are excellent. Have had them on a few bikes now. Look great and on high they are too hot on the hands, even in icy conditions.
The Triumph ones (if you can get them) are crap. My low setting gave up in the first or second year I had them and the high only seems to go to one side at a time. Save some money and frustration and go 3rd party.
Oops - sold out of 1" ones but still cheapest if you have other bikes or ATV's
You do need a stock throttle tube to be sourced from a used set of stock grips regularly available on ebay for under US$20 or free from a kind forum member and have to cut the throttle tube out of the right hand one to fit the cables. I forgot to take mine on the day I had the grips fitted at my dealer and they had a used one they fitted for free.
Still great prices on other items too like screen deflectors.
I've had Triumph heated grips on my 06 for 10 years now. Still work great
Other than the ugly switches, my only complaint is the grip are actually smaller in diameter than stock.