This Lot is 25pcs of New BI Technologies 50 Ohm Surface Mount POT in 4mm Square Package (detail size 5.0x4.5x2.7mm). Part Number: 23BR50-TR. 

• Resistance: 50 Ohm
• Power Handling: 0.25W
• Number of Turns: Single
• Adjustment Type: Top
• Resistive Material: Sealed Cermet
• Terminal Type: J leads
• Operating Temp: -55C to +125C
• Package Size: 5.0x4.5x2.7mm

Data sheet:

http://www.bitechnologies.com/pdfs/23.pdf