This is the Berg Microstamp 4L 4 Channel FM Micro Receiver from Castle Creations. FEATURES: Small and lightweight design yet still yields solid performance in harsh indoor RF environments, ParkFlying, or even at the flying field in your nitro powered models. Delivers full range so it is perfect for any 4-channel operation from small indoor electric models to full-blown glow powered models Auto detecting Positive or Negative Shift polarity Fail safe (programable ON and OFF) upon 2 seconds of no signal,servos move and hold to pre-programmed positions until signal returns Hold Mode (programable ON and OFF) all servos are held in positions of last known good signal before signal loss until signal returns INCLUDES: One Microstamp 4 channel receiver Two jumpers (used to program Fail Safe, Hold Mode & other operations) One Castle Creations logo decal REQUIRES: Castle Creations Berg Micro Crystals SPECS: Length: 1.35" (34mm) Width: .60" (16mm) Height: .35" (9mm) Weight: .14oz (4 grams) with wires Antenna wire length: 38" (965mm) Filtering: Triple tuned RF circuitry. Steep Flank 8-pole IF ceramic filter. True DSP Filtering in the microprocessor decoder with adaptive algorithms based on signal/noise ratio of the received signal Sensitivity: about 2uV kpm12/19/2005 ir/jxs