Fotodiox Pro 84mm 濾鏡支架保護蓋 - 相容於 Fotodiox Pro 84mm x 135mm 及 Cokin P-Series（M）系列濾鏡支架

I was skeptical about a dedicated filter holder cap, but this one slides right into the slot with no fuss and protects my Cokin P-Series setup perfectly.

Finally, a cap that actually stays snug in the slot and doesn't pop off when I toss the holder in my bag. The plastic feels sturdy enough to protect the threads without being too bulky.

I was worried the cap might rattle around in the slot, but it fits snugly and stays put in the 84mm x 135mm holder. Keeps the dust off the filter when I'm swapping lenses in the field, and it didn't add any bulk to my kit.