Retrofit smart locks are designed to smarten your deadbolt without replacing it entirely. It's a great concept for anyone just getting started with smart home technology, and we've seen August and Kwikset have success with their models. Candy House, a startup created by a Stanford University student, launched a kickstarter campaign in 2015 to create the Sesame Smart Lock. It's available for purchase now, and at $150 it's an affordable option, but not one I can recommend over August's more refined product line. The Sesame's $150 price converts to roughly £110 or AU$195.

The Sesame looks a lot like an old-fashioned kitchen timer. It comes in several colors and you have the option to label it with stickers to indicate which way to turn the lock to open or close it. The plastic construction of the lock and overall feel make it seem cheaper than any smart lock I've tested. The August Smart Lock, made from a combination of metal and plastic, costs $149, the same as the Sesame, and with its August Connect bridge priced at $80 and the Sesame's Wi-Fi Access Point priced at $70, there's just $10 difference between the two for the full combination of lock and Wi-Fi bridging accessory.

Chris Monroe/CNET

Finding a lock to test it on proved more difficult than I'd anticipated. While Candy House advertises that the Sesame works with "almost all cylinder deadbolts," I ran into an issue with the decorative plate and thumb latch size at the CNET Smart Home (video). The thumb latch didn't fit inside the dedicated portion of the lock designed to turn it. Candy House shows a gallery of locks on its website that the Sesame works with and while they might all technically fit, some would certainly look out of place or not sit flush with the mounting surface. I swapped out a deadbolt with a standard Kwikset model in order to test the Sesame. If you're going to purchase the Sesame Smart Lock, be sure to double-check the dimensions on the Candy House website before shelling out any cash.

The Sesame attaches to your door with an adhesive strip. That doesn't seem like the sturdiest approach for a piece of hardware that you physically turn and manipulate multiple times per day. The Sesame is powered by two CR123A 3V lithium batteries. The team at Candy House says the batteries are good for approximately 5,000 actions, which works out to around 500 days if you use your lock 10 times per day. It's not a hard battery size to find in stores, but it's certainly not as handy as the AA or AAA batteries you're likely to have lying around the house.