The LTH-301-05 is a transmissive phototransistor with 6mm aperture.
Specifications:
Slot Width: 6.0 mm
Aperture Width: 0.9 mm
Collector- Emitter Voltage VCEO Max: 30 V
Maximum Collector Current: 20 mA
If - Forward Current: 60 mA
Height: 11.6 mm
Length: 14 mm
Sensing Distance: 6 mm
Number of Channels: 1 Channel
Fall Time: 20 us
Rise Time: 15 us
Pd - Power Dissipation: 100 mW