The Sterling Silver snake chains I have available have a very small clasp at the hook end, allowing a pendant with a small opening to fit over the clasp very nicely.  They are available in the following lengths:

# 16" Snake         $8.00

# 18" Snake         $9.00

# 20" Snake       $11.00

# 24" Snake       $13.00

# 30" Snake       $15.00