In the original PlayStation 2 versions, Steel Poleyns are sold for 1,000 gil in Phon Coast and Old Archades. They are found in a treasure in Stilshrine of Miriam's Walk of Reason (northeast; 60% chance to appear, 45% chance for gil, 50% chance the item treasure is Steel Poleyns without the Diamond Armlet). They are a rare steal from Worgen and Alpha Worgen, and a possible reward from the Hunt Club sidequest on the Phon Coast (purchasable from the Shifty-Eyed Merchant's store after giving Stok five Rare Game trophies).
In the updated Zodiac versions, the Steel Poleyns are sold for 1,000 gil in Rabanastre's Clan Provisioner when the party has the rank of Headhunter within Clan Centurio. They are a treasure in Trial Mode stages 38 and 82 with the Diamond Armlet equipped. They can still be rarely stolen from Worgen and Alpha Worgen.
Steel Poleyns make traps safe, however, the party gets the same effect with Float, gained from the Float spell and the Winged Boots. It is more worthwhile to neutralize traps with Float than to use up an accessory slot for the Steel Poleyns.