1954 Gibson RB-250 5-string banjo with FON 8216-29. This is from the Reverb listing:
1954 GIBSON RB-250 – A very rare Banjo made in 1954 which was the first year that Gibson remanufactured their Mastertone banjo after WWII. Gibson made only 62 of these 5-String RB-250’s that year. FON 8216-29 In all original condition including the 4 hole arch top tone ring. The only thing not original is the bridge which is a Kat Eyz. The OHSC case is in mint condition with pink lining. A truly amazing banjo that sounds more like a flathead than an archtop.