This is one convenience store that is unlikely to be burgled.
Hao Mart, located at the void deck of Block 310, Yishun Ring Road, comes with reinforced walls and heavy steel doors that close with a resounding thud.
It is, after all, sited within a bomb shelter .
It is among the hundreds of public bomb shelters that mushroomed all over Singapore - at Housing Board void decks, MRT stations and in schools - in the 1980s. This was before a change of plans in September 1994 that heralded the start of individual shelters built inside new HDB flats for easier access.
Built for wartime, the common bomb shelters were largely kept empty at the start. But from the 1990s, they found a new lease of life, with the HDB renting them out for commercial use.
And these dusty and warm safe zones - with reinforced walls and large blast doors made of steel - have evolved into learning and shopping zones, thanks to their convenient locations.
The HDB and the Singapore Civil Defence Force (SCDF) said the Civil Defence Shelter Programme began in 1987, with a pilot phase where public shelters were built at the foot of HDB blocks.
To ensure the shelters are well utilised and maintained, they can be used during peace time. Doing so also helps raise awareness of the shelters and acquaint the public with their location and layout, said the authorities.
There are 177 basement shelters and 269 ground-level shelters scattered all over Singapore. There are also other types of shelters, such as those at MRT stations and schools.
Inspire Kids International childcare centre, which was launched in March last year, is situated inside such a shelter at the void deck of Block 851, Woodlands Street 83.
Its director, Ms Lydia Lim, 43, said they are not constrained by the shelter, adding: "We go to the nearby playground and the void deck for activities like games."
Ms Lim said they stay in only during lesson times and nap times.
"I feel that situating us here does contribute to making the neighbourhood more vibrant, due to the happiness and energy which the children exude."
The air ventilation system is good too, added Ms Lim, as the centre has windows and air-conditioning.
Fair Price Underground Superstore is located in a bomb shelter in the basement of Block 539, Hougang Street 52.
Supervisor Siao Le Xiang, 48, who has worked there for seven years, said the location is convenient.
"Some elderly residents cannot travel all the way to Hougang Mall, for example, to get their groceries, so it's very convenient for them."
Hougang Mall is about a 15-minute walk from the convenience store. "Some maids come here because their bosses would rather they not go too far away from home," added Ms Siao.
She explained that the main infrastructure is left untouched, such as the heavy metal door and its hinged frame, and the ventilation pipes that snake around the ceiling. They cannot hack away the walls to change the layout.
"But we had to add some lights to make it brighter, if not it is quite dim down here."
The shelters are regularly inspected by HDB.
Mr Ng Han Chuan, 33, supervisor of Hao Mart, said they have to follow strict guidelines. For instance, they must ensure that the toilets are functioning. The lights must also be in working condition, along with the air ventilation system.
"The authorities conduct checks about once a year to ensure they are in order," said Mr Ng.
According to SCDF and HDB, should the shelters be required during times of emergency, tenants will have 48 hours to remove their furniture, equipment and fixtures before handing over the premises to SCDF.
Mr Syahrin Abdullah, 22, who has just completed his full-time national service, shops at Fair Price Underground Superstore regularly. He lives a few blocks away, at Block 550.
"It's good because if something happens, we can come down here. Plus, it's already stocked with food and snacks," he said with a laugh.
According to HDB and SCDF, available shelters at void decks are rented out under term tenancies through an electronic bidding system. Interested applicants can bid at http://www.place2lease.com.
Mr Yang Iskandar Suratty, 42, principal tutor at Edufront Learning Centre, which is in a bomb shelter at Block 614, Elias Road, said they are not cheaper to rent compared with conventional spaces.
"We handle it like any typical venue and have to do everything to upkeep it. For example, if a bulb blows, we have to change it."
Operating out of a bomb shelter has another advantage.
While some of the venues hide the metal door behind grills, Mr Ng said that when they are done for the day, he would shut the heavy metal door with a loud thump.
"We have a separate main door at the front of the shop, but closing the big metal door makes it safer from theft and more secure, don't you think?"