The Y3 material used on the 537 switches is identical to the Y3X material. They are both UPE blends that come with fortified hardness and increased smoothness. The modified PA66 most likely has fiberglass added because the 537 switches sound quite clacky and full.
The 537 switch is manufactured using BSUN's newest stem and housing molds. The major differences compared to older BSUN switches include less stem wobble, better installation compatibility with most plate materials, and precise bottom-out with less interference.
1 quantity = 10 switches
Switch Type: Linear
Manufacturer: BSUN
Designer: Xida Studio
Stem material: New Y3
Top Housing: PC
Bottom Housing: Modified PA66
Operating Force: 45g±5g
Bottom-out Force: 51g±5g
Pre-travel: 1.9mm
Total Travel: 3.6mm
Spring: 20mm single-stage nickel-plated spring
Factory Lube: Yes. 205 and 105 mix on sliders. Dry film lube on the sliders of the stem and on the spring.
