Fuse-type taillight running bulb. 6 volt, 5 watt (38mm or 1.5 long).
You can look up your model in this bulb chart.
Fits models:
VNB VESPA 125 59 - 66 125 Large Frame - 8 in.
VNC Vespa Super 125 65 - 69 125 Large Frame - 8 in.
VNL Vespa GT / GTR 66 - 78 125 Large Frame - 10 in.
VBA Vespa 150 58 - 60 150 Large Frame - 8 in.
VBB Vespa 150 60 - 67 150 Large Frame - 8 in.
VBC Vespa Super 150 65 - 79 150 Large Frame - 8 in.
VLA Vespa GL 62 - 65 150 Large Frame - 10 in.
VLB Vespa Sprint 150 65 - 79 150 Large Frame - 10 in.
VS5 Vespa GS 150 58 - 61 150 Large Frame - 10 in.
VSB Vespa GS 160 62 - 64 160 Large Frame - 10 in.
VSD Vespa Rally 180 68 - 73 180 Large Frame - 10 in.
VSE Vespa Rally 200 72 - 79 200 Large Frame - 10 in.
V5A Vespa 50 63 - 83 50 Small Frame
V9A Vespa 90 63 - 84 90 Small Frame
V9B Vespa 100 Sport 78 - 84 100 Small Frame
VMA Vespa Primavera 65 - 83 125 Small Frame