The LT20-SP05-PK is a set of 10 black acetal rings sized to fit into LT20 and LH-2A 2-in. lens mounts. These washers are 0.5 mm thick and have a thin-wall design to maintain a 90% clear aperture.  The Acetal material is a low-friction, high-strength engineering plastic ideally suited as a protective washer and spacer for use with LT20-SP series aluminum lens spacers. 

LT20- sp05 - pk是一套10个黑色缩醛环大小适合LT20和LH-2A 2-in。镜头坐骑。这些垫圈厚0.5毫米，薄壁设计，保持90%的光圈。这种缩醛材料是一种低摩擦、高强度的工程塑料，非常适合用作LT20-SP系列铝透镜垫片的保护垫圈和垫片。