Maybe one of these similar products would be of interest:-

OPTURA HD OPTICS Professional 420-1600mm f/8.3 HD Manual Telephoto Lens for Pentax K-1, K-S2, K-S1, K-500, K-70, K-50, K-30, K5 IIs, K-7, K-5, K-3 II, K-2, K-X, K20D, K100D, K110D and K10D

Venus Laowa 25mm f/2.8 2.5-5X Ultra Macro for Pentax K Mount: Pentax K-1 Mark II, KP, K-70, K-30, K-1, K-5, K-3 II, K-S2, K-S1, etc.

Hersmay 420-800mm F/8.3-16 Telephoto Zoom Lens Manual Focus Super-Telephoto Lens for Pentax K K2000 K1000 K200D K-500 K100D K-50 K-30 K-20D K-7 K-5 K-5II K-5IIs K-3II K-3 K-S2 K-S1 K-r K-x K-m

OPTURA HD OPTICS OPTURA HD 500mm/1000mm f/8 Manual Telephoto Lens for Pentax K-1, K-S2, K-S1, K-500, K-70, K-50, K-30, K5 IIs, K-7, K-5, K-3 II, K-2, K-X, K20D, K100D, K110D and K10D (for Pentax)

Pentax AF fit Sigma DG 70-300mm Macro Autofocus lens, KAF K mount 1:2 Macro LZ25