MicroED datasets of spiro-O compound were collected using Talos Arctica (200 kV) with the CMOS camera Ceta. The stage was controlled using SerialEM and diffraction images were independently collected using Velox software. For this reason, only frames with constant rotation speed should be used for data processing. Rotation step (continuous) was ~0.95 or 1.52°/frame and tilt range was +/-15 or 30°. The calibrated camera length using Al powder was 793.52 (data 190719 & 190812) or 819.71 (data 190928) mm. Crystals belonged to space group P-1 with a~12.4, b~15.0, c~15.3 Å, α=79.6, β=83.7, γ=87.3°. Finally 25 datasets were merged at ~0.95 Å resolution (Hamada et al., 2020; CCDC 1986103). Collection condition: gun lens 4, spot 10, C2: parallel beam condition, 0.19 e/A^2/sec, total ~15 e/A^2 Note: EMD files (hdf5 format) were transparently compressed using h5repack -f SHUF -f GZIP=4 command to reduce file size. EMD file can be processed with DIALS using this dxtbx format file. Metadata (machine parameters, stage tilt angles etc.) is stored as json format in /Data/Image/*/Metadata in emd file. See here for details.