STC adds 6-stop neutral density to its clip-on sensor filter range: Digital Photography Review
Kase Clip-In ND8 Filter for Sony a6000, a6100, a6400, 1121040010
Kase Clip in CMOS Protector MCUV/Neutral Density ND1000 ND64/Light Pollution Filter for Sony A7/A7III/A7RIII/A7R/A9/FX3 Camera|Camera Filters| - AliExpress