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Available both stock/untouched and Heat Rolled with Progressive Pressure - choose your preference during checkout!
The Proton Series 4 Yee Yee USSSA Slowpitch Softball Bat brings serious performance to the field with a bold Yee Yee camo design that’s impossible to miss. Built with Proton’s latest Series 4 Technology, this two-piece composite bat is engineered for high-level performance, consistency, and durability.
Featuring a versatile 12.75-inch barrel, the Series 4 Yee Yee gives hitters a strong combination of barrel control and hitting surface. Choose from Balanced, 0.5 oz End Load, or Full 1 oz End Load options to match your swing style and preferred feel through the zone.
Available in 25 oz, 26 oz, and 27 oz models and certified for USSSA, NSA, and ISA play, the Yee Yee Series 4 is built for players looking to bring Proton’s maximum allowable performance to the plate.
- Brand: Proton
- Diameter: 2-1/4 inch
- Certification: USSSA, NSA, ISA Leagues & Tournaments
- Two-piece composite construction for independent barrel flex and reduced hand vibration
- Built to maximum allowable performance under the USSSA standard
- Aerospace-grade carbon fiber engineered by aerospace and defense industry engineers
- Proton's guarantee that the bat will pass, last, and perform
- 12.75 inch barrel length for balanced coverage and swing speed
- Year Released: 2026
- Adding our Heat Roll with Progressive Pressure to your order may cause decertification, check with the governing body of your league for clarification
Manufacturing tolerances, performance considerations, and grip weight may cause variations from the listed weight.
QUESTION: Should I order this bat stock/untouched or Heat Rolled with Progressive Pressure?
ANSWER: If you order your new bat Heat Rolled with Progressive Pressure, it will be delivered to you completely and evenly broken in. This process adds 20-40ft of distance to your solid hits, increases consistency, improves durability and adds 2-3 business days of lead time to your order. If you plan to use the bat in an official game or event, please verify the legality of our process with your league or sanctioning body before use. We (LongballBats.com) do not encourage the use of a Heat Rolled bat in any game or event where it is against the rules. Click here for details about our process!
QUESTION: Which end load should I get: Balanced, Half Ounce, or Full Ounce?
ANSWER: Match it to your swing, not your ego. Balanced spreads the weight evenly along the bat, keeps your hands quick, and gives you the most control, which suits contact and gap hitters. Half Ounce shifts a modest amount of mass toward the end cap for more energy at contact while staying manageable for most players, and it is the safe pick if you are unsure. Full Ounce is a true power-hitter swing weight that rewards a strong hitter with a full swing path and punishes anyone who cannot keep bat speed up with it. A useful rule: if you have never swung an end load, start at Half Ounce. If you have swung one for years and want more, go Full. Total ounce weight and end load are separate choices, so a lighter total weight with a heavier load is a legitimate way to get power feel without an unwieldy bat.
