The ScyTek A20 has all the basic features we look for in an affordable car alarm: a 120-dB six-stage siren, dual-zone impact sensors and keyless entry. The ScyTek A20 remote is among the smallest available despite having five functional buttons. Unfortunately, the manufacturer offers only very limited customer support, and the website is difficult to navigate.
Similar to the Avital 3100LX and the Pyle PWD701, the ScyTek A20 features a smart dual-zone impact sensor capable of differentiating between small and big impacts. If someone bumps into your car while they're walking through a parking lot, they receive a warning chirp. But if they try to open a door, the full six-stage alarm goes off.
While the car alarm doesn't have window or shock sensors, it is compatible with these as add-ons. That said, it only has two auxiliary ports, so you can't add as many additional sensors or functions as more expensive car alarms. But if you're not happy with the current sensor, you can upgrade the system as you go without having to replace everything, or you can use the ports to add a remote-start system or keyless entry.
The remote for the A20 is one way. This means it doesn't receive alerts from the alarm, but only sends signals to activate or disarm the alarm. The downside to a one-way remote is you never know when the alarm has gone off. Every time you hear a car alarm, you must investigate whether it's coming from your car. However, it is compatible with ScyTek's two-way remotes, so you can upgrade, though this takes one of the two auxiliary ports.
The A20 comes with two very small one-way remotes. The manufacturer doesn't list the range, but user reviews indicate it's somewhere between 200 and 500 feet. By comparison, the shortest listed range of a car alarm is 1,500 feet and the longest is a mile. Many users have complained about the short range.
The car alarm system is compatible with a wide array of convenience features, but these are all optional and add to the cost. The keyless entry is marketed as a feature, but it's optional, as is the trunk release. All these require additional wiring and take one of the two auxiliary ports, so you have to be judicious about the optional features you want.
The ScyTek A20 is a good option for a $30 car alarm. The security options are basic but no less effective than a more expensive car alarm. They all have dual-stage shock sensors and a 120-dB siren. If all you're looking for in a car security system is the alarm, then there's no reason to spend more. That said, the range of the remote is poor and all the common convenience features, such as remote start and keyless entry, are options costing extra, and you can only add two addition features because it only has two auxiliary ports.