All sizes are displayed in their UK format. EU sizes may differ.\nSena Spider RT1 Mesh Bluetooth Motorcycle Helmet Intercom Comms System\nIntroducing the Sena Spider RT1 motorcycle mesh Bluetooth intercom system, an affordable low-profile headset with a sleek three-button control by Sena. The Spider RT1 and the jog-dial equipped Spider ST1 are Sena's first motorcycle communication headsets operating exclusively on the ground breaking Mesh Intercom\u2122 platform.\nSena's premium Mesh technology, as first seen in the flagship 50S and 50R headsets, streamlines rider-to-rider communication for large and small groups and now delivers that same robust reliability for all Spider RT1 users.\nSena Spider RT1 Mesh Bluetooth Intercom System Features:\n--Main module dimensions: 97 x 48 x 27 mm\n--Speaker driver unit dimensions: 40 x 7.2 mm\n--Wired boom microphone length: 150 mm\n--Wire between speakers length: 555 mm\n--Main module weight: 65 grams\n--Operating temperature: -10-55\u00B0C\n--Me.