Great inexpensive multi channel receiver. A lot of people have been using this on crawlers to utilize the extra channels on their remotes (7px, 10px)

R2106GF– S-FHSS 2.4 GHz System 6-Channel Air Receiver

S-FHSS/FHSS (Auto Detection)

SIZE:
21.5 mm x 38.8 mm x 10.7 mm
0.85 in x 1.53 in x 0.42 in

WEIGHT:
4.5 g
0.16 oz

OPERATING VOLTAGE (TYP.):
DC 4.8V~7.4V