Lens Caps

Models

35mm - TD Digital (Top Lens)

50mm - TD Thermal (Lower Lens)

40mm - 

Night Stalker 4K Series (Not Pro or Ex) - Screw in Type Only (If in doubt email a picture)

If its just the cap broken and you have the clip inside, then this will work for either

TA35 - TA Series 35 Lens (LRF or non LRF) 

TA19 or 25 Series - 19 or 25 Lens (LRF or non LRF)