This is a listing of the types of batteries used in Sekonic meters.  Mercury batteries are no longer made.  There are Wein or "hearing aid" batteries.  They use "air" to activate them.  So some people suggest only opening one or two holes as the meter use very little power.  BUT, you may need to put an "air hole" in the battery cover to allow air to circulate.
There are new adapters that hold standard 1.5V batteries and drop the voltage to the correct level.  The adapters last forever, you just replace the inexpensive battery.  Some of the adapters are just "spacers" that correctly fit the old batteries but use current smaller batteries with the same voltage.

Meter

Name

Battery

Non- Mercury Replacement

From

To
L-88 MICRO-LIGHTMETER 1.35V H-N battery  Small Battery Company MR-52 Adapter  1961 1963
L-96 SUPER-MICROLITE 1.35V H-N battery Small Battery Company MR-52 Adapter   1961 1964
L-98 MICRO-LEADER 1.35V PX-13 WeinCell MBR625 or CHRIS Adapter MR-9 1964 1978
L-136 MICROCLIP-ON 1.35V PX-13 WeinCell MBR625 or CHRIS Adapter MR-9 1962 1970
L-164B MARINEMETER II 1.35V PX-13 WeinCell MBR625 or CHRIS Adapter MR-9 1969 2002
L-188 AUTO-LEADER 1.5V G-13 or MS-76   1979 2005
L-206 VIEWMETER 1.35V Mercury (H-R) No info available 1966 1976
L-208 TWINMATE 3V CR2032   2000 present
L-216 AUTORANGE 1.35V PX-13 WeinCell MBR625 or CHRIS Adapter MR-9 1966 1978
L-218 APEX 1.35V PX-13 WeinCell MBR625 or CHRIS Adapter MR-9 1967 1979
L-228 ZOOM-METER 1.35V PX-13 (2) WeinCell MBR625 (2) or CHRIS Adapter MR-9 (2) 1968 1985
L-248 MULTI-LUMI 1.35V PX-13 WeinCell MBR625 or CHRIS Adapter MR-9 1971 1992
L-256 FLASHMETER 5.6V164DX CHRIS Adapter HM-4N 1972 1985
L-308 FLASHMATE 1.5V AA   1992 present
L-318 DIGI-LITE 1.5V AA   1986 2002
L-328 DIGI-LITE F 1.5V AA   1988 2002
L-358 FLASHMASTER 3V CR123A   2001 present
L-408 MULTIMASTER 1.5V AA   1995 2002
L-418 AUTOMETER 1.5V AA   1977 1980
L-428 SYSTEM-METER 1.5V G-13 or MS-76 (4)   1974 1985
L-438 VIEW-SPOTMETER 1.5V AA   1979 1988
L-448 STUDIO-AUTO II 1.5V AA   1981 1985
L-458 DIGI-FLASH 1.5V AA   1984 1989
L-488 DIGI-SPOT 1.5V AA (2)   1985 1991
L-508 ZOOM-MASTER 1.5V AA   1997 2003
L-508Cine CINE ZOOM-MASTER 1.5V AA   1998 2003
L-518 DIGIPRO X-1 1.5V AA   1983 1989
L-558/
L-558R		 DUALMASTER 3V CR123A 2003 present
L-558Cine CINE DUALMASTER 3V CR123A 2003 present
L-608 SUPERZOOM-MASTER 3V CR123A   2001 2004
L-608Cine CINE SUPERZOOM-MASTER 3V CR123A   2001 2004
L-718 DIGI-MASTER 1.5V AA (2)   1990 2001
L-778 DUAL-SPOT F 1.5V AA (2)   1992 2002