ticket prices:

Adults:
24 Hours Ticket:  RM45 (Malaysian: RM19)
48 Hours Ticket: RM79 (Malaysian: RM32)

Child (5-12 years), Students, Disabled:
24 Hours Ticket:  RM19 (Malaysian: RM12)
48 Hours Ticket: RM32 (Malaysian: RM20)

Ticket Online Booking

KL Hop-on Hop-off Bus in Bukiit Bintang
 

route map

some of the buses, like this one, have open decks at the back

watch out for the purple bus stop sign

bus stops:
1) Malaysia Tourism Information Centre
2) KL Tower
3) Jalan P. Ramlee
4) KL Concention Centre & Aquaria
5) Karyaneka
6) Bintang Walk
7) Tengkat Tong Shin
8) Chinatown
9) Central Market
10) Little India
11) KL Sentral
12) National Museum
13) National Palace
14) Lake Gardens
15) Bird Park
16) National Mosque
17) Dataran Merdeka (Square)
18) Medan Mara
19) Jalan Raja Laut
20) Bulatan Pahang
21) Lake Titiwangsa
22) Citi Bank
23) KLCC