New redesigned drop in seal also suitable for some gas spring guns ( RX1-2, HW90 UK) and the Theoben R1-80 kit as well . Designed for both old and new guns as well as the many with tube tolerance issues. Older Hw35's with leather seals require an adapter for fitting the newer style seals.
New design better handles the out of spec guns with tube issues. Common place today unfortunately. Design incorporates rear lubricant retaining ring and wiper- parachuted front groove to easily adapt to tube flat spots and out of round receivers and helps the seal find an ideal area to settle into like the factory seal. 1.198" OD but squeezes down below 30mm if required.