The Blam CRS27A is a spare-tire active subwoofer built into a cast aluminium enclosure with an integrated amplifier delivering up to 300 W peak and 150 W nominal. The package includes an external remote level control and a 30 cm connector accessory kit.

The unit is designed for installation in a vehicle spare-tire well and accepts RCA low-level inputs (0.4-4 V) and high-level inputs with auto turn-on, plus features adjustable bass boost, a fixed 20 Hz subsonic filter, a 50-150 Hz low-pass filter and phase selection.