This article refers to the replaceable fuse in the L1 Classic and L1 Model I.

fuses
fuses

Specifications

Chuck-at-Bose tells us

It's a T15A, 125V/250V, 6.3x32mm

Or buy them direct from Bose - Part Number: '''044180'''


There are no customer replaceable fuses in the L1 Model II or L1 Compact.