Ok, got it about a week ago and it fits any standard 1mw green laser (the ones that are built to look like a pen) that they sell on eBay for a coupla bucks. Everyone I have spoken to (folks at Bintel, other astronomers) say the 1mw laser is useless but I found mine to be highly visible (even in my light-polluted Melbournian backyard), so I have no complaints whatsoever. Hope this helps someone in future to decide.
For the particular model of laser that I have (
http://www.ebay.com.au/itm/280980740...84.m1439.l2649 ), the back end screws off to get to the battery compartment. Thankfully, this sits just beyond the locking screws on the laser mount, so I can change the batteries without having to realign the laser mount to the telescope.