I can’t seem to find the HiRise in Singapore, even Apple Singapore and Hong Kong Online Store doesn’t list the product. You best bet is to get the product directly from Twelve South website itself for US$79.99 (S$99) excluding shipping of about US$45 to Singapore.
The installation of the HiRise is even simpler than the BackPack 2.
One nice touch by Twelve South is they added 8 small but strong magnets (4 on the front panel and 4 on the back panel) so that you can remove and attach the panels with ease. The panels also comes with 4 screw holes each to let you have the option of using the provided screws if you do not want to use it as a storage space.