This supplement is 18 pages, including cover and OGL on the last page. There are several illustrations, charts, and tables. It deals with various aspects of combat, with suggested house rule changes to craft combat to your liking.
It begins with the combat round and moves on to mounted combat, unmounting a rider, fisticuffs, grappling, called shots, disarming opponents, permanent damage and maiming, parting shots, shield wall, ranged combat, critical hits, death and dying, weapon proficiencies, specialization, fighting styles, running competitive combats, such as jousts, tournaments, and archery,
Most of these rules are a paragraph or two. They can be used whole cloth, or a piece here and there, or server for ideas for your own rules.
The majority of these rules are more fiddly than I prefer in the combat system. The last section on jousts, tournaments, and archery would get the most use in my campaign.
If you are looking for house rules that are balanced and fit in with OD&D clones, such as Swords & Wizardry, this booklet will give you lots of ideas.