X0508 4 2025-08-01 false 0001555279 908 Devices Inc. MASS 0002081945 Vann Brandi C C/O 908 DEVICES INC. 44 THIRD AVENUE BURLINGTON MA 01803 true false false false false Restricted Stock Unit 2025-08-01 4 A false 15577.00 0.00 A Common Stock 15577.00 15577.00 D Stock Option (option to buy) 5.14 2025-08-01 4 A false 20409.00 0.00 A 2025-07-31 Common Stock 20409.00 20409.00 D Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested. This Form 4 is being filed late due to an inadvertent administrative error. The RSUs become vested in substantially equal annual installments over the 3 years following August 1, 2025, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date. The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 36 months following August 1, 2025, subject to the reporting person's continued service through the applicable vesting date. /s/ Michael S. Turner, as Attorney-in-Fact 2025-08-18