şlem

/ʃlem/

Cases

SingularPluralWhen to use it
nominativeşlemthe helmetşlemlethe helmetsthe plain dictionary form — the doer of the sentence
genitiveşlemnithe helmet'sşlemlenithe helmets'the owner — whose it is
accusativeşlemnithe helmet (as the object)şlemlenithe helmets (as the object)a specific, known object — whom or what
dativeşlemgeto the helmetşlemlegeto the helmetsdirection or recipient — to where, to whom
locativeşlemdeat / in the helmetşlemledeat / in the helmetswhere it is; also having — mende bar, "I have it"
ablativeşlemdenfrom the helmetşlemledenfrom the helmetswhere it comes from; also "than" when comparing
When to use each case
nominative
the plain dictionary form — the doer of the sentence
genitive
the owner — whose it is
accusative
a specific, known object — whom or what
dative
direction or recipient — to where, to whom
locative
where it is; also having — mende bar, "I have it"
ablative
where it comes from; also "than" when comparing

The endings are the same ones the pronouns wear — that page explains when each case is used.

With an owner

One ownedSeveral owned
myşlemimmy helmetşlemlerimmy helmets
yourşlemingyour helmetşlemleringyour helmets
his / herşlemihis / her helmetşlemlerihis / her helmets
ourşlemibizour helmetşlemleribizour helmets
you all'sşlemigizyou all's helmetşlemlerigizyou all's helmets
theirşlemleritheir helmetşlemleritheir helmets

The overlap in the last rows is real, not a mistake: şlemleri can mean "his / her helmets", "their helmet", or "their helmets" — context decides.